From 414b4ff5eecff0097d09c4a7da12e435fd503692 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 25 Jan 2011 12:43:49 +0100 Subject: block: add REQ_FLUSH_SEQ rq == &q->flush_rq was used to determine whether a rq is part of a flush sequence, which worked because all requests in a flush sequence were sequenced using the single dedicated request. This is about to change, so introduce REQ_FLUSH_SEQ flag to distinguish flush sequence requests. This patch doesn't cause any behavior change. Signed-off-by: Tejun Heo Signed-off-by: Jens Axboe --- block/blk-core.c | 4 ++-- block/blk-flush.c | 1 + block/blk.h | 2 +- 3 files changed, 4 insertions(+), 3 deletions(-) (limited to 'block') diff --git a/block/blk-core.c b/block/blk-core.c index 4ce953f..fc7d8ad 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -136,7 +136,7 @@ static void req_bio_endio(struct request *rq, struct bio *bio, { struct request_queue *q = rq->q; - if (&q->flush_rq != rq) { + if (!(rq->cmd_flags & REQ_FLUSH_SEQ)) { if (error) clear_bit(BIO_UPTODATE, &bio->bi_flags); else if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) @@ -1789,7 +1789,7 @@ static void blk_account_io_done(struct request *req) * normal IO on queueing nor completion. Accounting the * containing request is enough. */ - if (blk_do_io_stat(req) && req != &req->q->flush_rq) { + if (blk_do_io_stat(req) && !(req->cmd_flags & REQ_FLUSH_SEQ)) { unsigned long duration = jiffies - req->start_time; const int rw = rq_data_dir(req); struct hd_struct *part; diff --git a/block/blk-flush.c b/block/blk-flush.c index 54b123d..8592869 100644 --- a/block/blk-flush.c +++ b/block/blk-flush.c @@ -130,6 +130,7 @@ static struct request *queue_next_fseq(struct request_queue *q) BUG(); } + rq->cmd_flags |= REQ_FLUSH_SEQ; elv_insert(q, rq, ELEVATOR_INSERT_FRONT); return rq; } diff --git a/block/blk.h b/block/blk.h index 2db8f32..9d2ee8f 100644 --- a/block/blk.h +++ b/block/blk.h @@ -61,7 +61,7 @@ static inline struct request *__elv_next_request(struct request_queue *q) while (!list_empty(&q->queue_head)) { rq = list_entry_rq(q->queue_head.next); if (!(rq->cmd_flags & (REQ_FLUSH | REQ_FUA)) || - rq == &q->flush_rq) + (rq->cmd_flags & REQ_FLUSH_SEQ)) return rq; rq = blk_do_flush(q, rq); if (rq) -- cgit v1.1 From 143a87f4c9c629067afea5b6703d66ea88c82f8e Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 25 Jan 2011 12:43:52 +0100 Subject: block: improve flush bio completion bio's for flush are completed twice - once during the data phase and one more time after the whole sequence is complete. The first completion shouldn't notify completion to the issuer. This was achieved by skipping all bio completion steps in req_bio_endio() for the first completion; however, this has two drawbacks. * Error is not recorded in bio and must be tracked somewhere else. * Partial completion is not supported. Both don't cause problems for the current users; however, they make further improvements difficult. Change req_bio_endio() such that it only skips the actual notification part for the first completion. bio completion is implemented with partial completions on mind anyway so this is as simple as moving the REQ_FLUSH_SEQ conditional such that only calling of bio_endio() is skipped. Signed-off-by: Tejun Heo Signed-off-by: Jens Axboe --- block/blk-core.c | 48 +++++++++++++++++++++--------------------------- 1 file changed, 21 insertions(+), 27 deletions(-) (limited to 'block') diff --git a/block/blk-core.c b/block/blk-core.c index fc7d8ad..617bb9e4 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -136,37 +136,31 @@ static void req_bio_endio(struct request *rq, struct bio *bio, { struct request_queue *q = rq->q; - if (!(rq->cmd_flags & REQ_FLUSH_SEQ)) { - if (error) - clear_bit(BIO_UPTODATE, &bio->bi_flags); - else if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) - error = -EIO; - - if (unlikely(nbytes > bio->bi_size)) { - printk(KERN_ERR "%s: want %u bytes done, %u left\n", - __func__, nbytes, bio->bi_size); - nbytes = bio->bi_size; - } + if (error) + clear_bit(BIO_UPTODATE, &bio->bi_flags); + else if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) + error = -EIO; + + if (unlikely(nbytes > bio->bi_size)) { + printk(KERN_ERR "%s: want %u bytes done, %u left\n", + __func__, nbytes, bio->bi_size); + nbytes = bio->bi_size; + } - if (unlikely(rq->cmd_flags & REQ_QUIET)) - set_bit(BIO_QUIET, &bio->bi_flags); + if (unlikely(rq->cmd_flags & REQ_QUIET)) + set_bit(BIO_QUIET, &bio->bi_flags); - bio->bi_size -= nbytes; - bio->bi_sector += (nbytes >> 9); + bio->bi_size -= nbytes; + bio->bi_sector += (nbytes >> 9); - if (bio_integrity(bio)) - bio_integrity_advance(bio, nbytes); + if (bio_integrity(bio)) + bio_integrity_advance(bio, nbytes); - if (bio->bi_size == 0) - bio_endio(bio, error); - } else { - /* - * Okay, this is the sequenced flush request in - * progress, just record the error; - */ - if (error && !q->flush_err) - q->flush_err = error; - } + /* don't actually finish bio if it's part of flush sequence */ + if (bio->bi_size == 0 && !(rq->cmd_flags & REQ_FLUSH_SEQ)) + bio_endio(bio, error); + else if (error && !q->flush_err) + q->flush_err = error; } void blk_dump_rq_flags(struct request *rq, char *msg) -- cgit v1.1 From ae1b1539622fb46e51b4d13b3f9e5f4c713f86ae Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 25 Jan 2011 12:43:54 +0100 Subject: block: reimplement FLUSH/FUA to support merge The current FLUSH/FUA support has evolved from the implementation which had to perform queue draining. As such, sequencing is done queue-wide one flush request after another. However, with the draining requirement gone, there's no reason to keep the queue-wide sequential approach. This patch reimplements FLUSH/FUA support such that each FLUSH/FUA request is sequenced individually. The actual FLUSH execution is double buffered and whenever a request wants to execute one for either PRE or POSTFLUSH, it queues on the pending queue. Once certain conditions are met, a flush request is issued and on its completion all pending requests proceed to the next sequence. This allows arbitrary merging of different type of flushes. How they are merged can be primarily controlled and tuned by adjusting the above said 'conditions' used to determine when to issue the next flush. This is inspired by Darrick's patches to merge multiple zero-data flushes which helps workloads with highly concurrent fsync requests. * As flush requests are never put on the IO scheduler, request fields used for flush share space with rq->rb_node. rq->completion_data is moved out of the union. This increases the request size by one pointer. As rq->elevator_private* are used only by the iosched too, it is possible to reduce the request size further. However, to do that, we need to modify request allocation path such that iosched data is not allocated for flush requests. * FLUSH/FUA processing happens on insertion now instead of dispatch. - Comments updated as per Vivek and Mike. Signed-off-by: Tejun Heo Cc: "Darrick J. Wong" Cc: Shaohua Li Cc: Christoph Hellwig Cc: Vivek Goyal Cc: Mike Snitzer Signed-off-by: Jens Axboe --- block/blk-core.c | 10 +- block/blk-flush.c | 440 +++++++++++++++++++++++++++++++++++++----------------- block/blk.h | 12 +- block/elevator.c | 7 + 4 files changed, 319 insertions(+), 150 deletions(-) (limited to 'block') diff --git a/block/blk-core.c b/block/blk-core.c index 617bb9e4..0574609 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -134,8 +134,6 @@ EXPORT_SYMBOL(blk_rq_init); static void req_bio_endio(struct request *rq, struct bio *bio, unsigned int nbytes, int error) { - struct request_queue *q = rq->q; - if (error) clear_bit(BIO_UPTODATE, &bio->bi_flags); else if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) @@ -159,8 +157,6 @@ static void req_bio_endio(struct request *rq, struct bio *bio, /* don't actually finish bio if it's part of flush sequence */ if (bio->bi_size == 0 && !(rq->cmd_flags & REQ_FLUSH_SEQ)) bio_endio(bio, error); - else if (error && !q->flush_err) - q->flush_err = error; } void blk_dump_rq_flags(struct request *rq, char *msg) @@ -519,7 +515,9 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) init_timer(&q->unplug_timer); setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q); INIT_LIST_HEAD(&q->timeout_list); - INIT_LIST_HEAD(&q->pending_flushes); + INIT_LIST_HEAD(&q->flush_queue[0]); + INIT_LIST_HEAD(&q->flush_queue[1]); + INIT_LIST_HEAD(&q->flush_data_in_flight); INIT_WORK(&q->unplug_work, blk_unplug_work); kobject_init(&q->kobj, &blk_queue_ktype); @@ -1198,7 +1196,7 @@ static int __make_request(struct request_queue *q, struct bio *bio) spin_lock_irq(q->queue_lock); if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) { - where = ELEVATOR_INSERT_FRONT; + where = ELEVATOR_INSERT_FLUSH; goto get_rq; } diff --git a/block/blk-flush.c b/block/blk-flush.c index 8592869..a867e3f 100644 --- a/block/blk-flush.c +++ b/block/blk-flush.c @@ -1,6 +1,69 @@ /* * Functions to sequence FLUSH and FUA writes. + * + * Copyright (C) 2011 Max Planck Institute for Gravitational Physics + * Copyright (C) 2011 Tejun Heo + * + * This file is released under the GPLv2. + * + * REQ_{FLUSH|FUA} requests are decomposed to sequences consisted of three + * optional steps - PREFLUSH, DATA and POSTFLUSH - according to the request + * properties and hardware capability. + * + * If a request doesn't have data, only REQ_FLUSH makes sense, which + * indicates a simple flush request. If there is data, REQ_FLUSH indicates + * that the device cache should be flushed before the data is executed, and + * REQ_FUA means that the data must be on non-volatile media on request + * completion. + * + * If the device doesn't have writeback cache, FLUSH and FUA don't make any + * difference. The requests are either completed immediately if there's no + * data or executed as normal requests otherwise. + * + * If the device has writeback cache and supports FUA, REQ_FLUSH is + * translated to PREFLUSH but REQ_FUA is passed down directly with DATA. + * + * If the device has writeback cache and doesn't support FUA, REQ_FLUSH is + * translated to PREFLUSH and REQ_FUA to POSTFLUSH. + * + * The actual execution of flush is double buffered. Whenever a request + * needs to execute PRE or POSTFLUSH, it queues at + * q->flush_queue[q->flush_pending_idx]. Once certain criteria are met, a + * flush is issued and the pending_idx is toggled. When the flush + * completes, all the requests which were pending are proceeded to the next + * step. This allows arbitrary merging of different types of FLUSH/FUA + * requests. + * + * Currently, the following conditions are used to determine when to issue + * flush. + * + * C1. At any given time, only one flush shall be in progress. This makes + * double buffering sufficient. + * + * C2. Flush is deferred if any request is executing DATA of its sequence. + * This avoids issuing separate POSTFLUSHes for requests which shared + * PREFLUSH. + * + * C3. The second condition is ignored if there is a request which has + * waited longer than FLUSH_PENDING_TIMEOUT. This is to avoid + * starvation in the unlikely case where there are continuous stream of + * FUA (without FLUSH) requests. + * + * For devices which support FUA, it isn't clear whether C2 (and thus C3) + * is beneficial. + * + * Note that a sequenced FLUSH/FUA request with DATA is completed twice. + * Once while executing DATA and again after the whole sequence is + * complete. The first completion updates the contained bio but doesn't + * finish it so that the bio submitter is notified only after the whole + * sequence is complete. This is implemented by testing REQ_FLUSH_SEQ in + * req_bio_endio(). + * + * The above peculiarity requires that each FLUSH/FUA request has only one + * bio attached to it, which is guaranteed as they aren't allowed to be + * merged in the usual way. */ + #include #include #include @@ -11,185 +74,290 @@ /* FLUSH/FUA sequences */ enum { - QUEUE_FSEQ_STARTED = (1 << 0), /* flushing in progress */ - QUEUE_FSEQ_PREFLUSH = (1 << 1), /* pre-flushing in progress */ - QUEUE_FSEQ_DATA = (1 << 2), /* data write in progress */ - QUEUE_FSEQ_POSTFLUSH = (1 << 3), /* post-flushing in progress */ - QUEUE_FSEQ_DONE = (1 << 4), + REQ_FSEQ_PREFLUSH = (1 << 0), /* pre-flushing in progress */ + REQ_FSEQ_DATA = (1 << 1), /* data write in progress */ + REQ_FSEQ_POSTFLUSH = (1 << 2), /* post-flushing in progress */ + REQ_FSEQ_DONE = (1 << 3), + + REQ_FSEQ_ACTIONS = REQ_FSEQ_PREFLUSH | REQ_FSEQ_DATA | + REQ_FSEQ_POSTFLUSH, + + /* + * If flush has been pending longer than the following timeout, + * it's issued even if flush_data requests are still in flight. + */ + FLUSH_PENDING_TIMEOUT = 5 * HZ, }; -static struct request *queue_next_fseq(struct request_queue *q); +static bool blk_kick_flush(struct request_queue *q); -unsigned blk_flush_cur_seq(struct request_queue *q) +static unsigned int blk_flush_policy(unsigned int fflags, struct request *rq) { - if (!q->flush_seq) - return 0; - return 1 << ffz(q->flush_seq); + unsigned int policy = 0; + + if (fflags & REQ_FLUSH) { + if (rq->cmd_flags & REQ_FLUSH) + policy |= REQ_FSEQ_PREFLUSH; + if (blk_rq_sectors(rq)) + policy |= REQ_FSEQ_DATA; + if (!(fflags & REQ_FUA) && (rq->cmd_flags & REQ_FUA)) + policy |= REQ_FSEQ_POSTFLUSH; + } + return policy; } -static struct request *blk_flush_complete_seq(struct request_queue *q, - unsigned seq, int error) +static unsigned int blk_flush_cur_seq(struct request *rq) { - struct request *next_rq = NULL; - - if (error && !q->flush_err) - q->flush_err = error; - - BUG_ON(q->flush_seq & seq); - q->flush_seq |= seq; - - if (blk_flush_cur_seq(q) != QUEUE_FSEQ_DONE) { - /* not complete yet, queue the next flush sequence */ - next_rq = queue_next_fseq(q); - } else { - /* complete this flush request */ - __blk_end_request_all(q->orig_flush_rq, q->flush_err); - q->orig_flush_rq = NULL; - q->flush_seq = 0; - - /* dispatch the next flush if there's one */ - if (!list_empty(&q->pending_flushes)) { - next_rq = list_entry_rq(q->pending_flushes.next); - list_move(&next_rq->queuelist, &q->queue_head); - } - } - return next_rq; + return 1 << ffz(rq->flush.seq); } -static void blk_flush_complete_seq_end_io(struct request_queue *q, - unsigned seq, int error) +static void blk_flush_restore_request(struct request *rq) { - bool was_empty = elv_queue_empty(q); - struct request *next_rq; - - next_rq = blk_flush_complete_seq(q, seq, error); - /* - * Moving a request silently to empty queue_head may stall the - * queue. Kick the queue in those cases. + * After flush data completion, @rq->bio is %NULL but we need to + * complete the bio again. @rq->biotail is guaranteed to equal the + * original @rq->bio. Restore it. */ - if (was_empty && next_rq) - __blk_run_queue(q); + rq->bio = rq->biotail; + + /* make @rq a normal request */ + rq->cmd_flags &= ~REQ_FLUSH_SEQ; + rq->end_io = NULL; } -static void pre_flush_end_io(struct request *rq, int error) +/** + * blk_flush_complete_seq - complete flush sequence + * @rq: FLUSH/FUA request being sequenced + * @seq: sequences to complete (mask of %REQ_FSEQ_*, can be zero) + * @error: whether an error occurred + * + * @rq just completed @seq part of its flush sequence, record the + * completion and trigger the next step. + * + * CONTEXT: + * spin_lock_irq(q->queue_lock) + * + * RETURNS: + * %true if requests were added to the dispatch queue, %false otherwise. + */ +static bool blk_flush_complete_seq(struct request *rq, unsigned int seq, + int error) { - elv_completed_request(rq->q, rq); - blk_flush_complete_seq_end_io(rq->q, QUEUE_FSEQ_PREFLUSH, error); + struct request_queue *q = rq->q; + struct list_head *pending = &q->flush_queue[q->flush_pending_idx]; + bool queued = false; + + BUG_ON(rq->flush.seq & seq); + rq->flush.seq |= seq; + + if (likely(!error)) + seq = blk_flush_cur_seq(rq); + else + seq = REQ_FSEQ_DONE; + + switch (seq) { + case REQ_FSEQ_PREFLUSH: + case REQ_FSEQ_POSTFLUSH: + /* queue for flush */ + if (list_empty(pending)) + q->flush_pending_since = jiffies; + list_move_tail(&rq->flush.list, pending); + break; + + case REQ_FSEQ_DATA: + list_move_tail(&rq->flush.list, &q->flush_data_in_flight); + list_add(&rq->queuelist, &q->queue_head); + queued = true; + break; + + case REQ_FSEQ_DONE: + /* + * @rq was previously adjusted by blk_flush_issue() for + * flush sequencing and may already have gone through the + * flush data request completion path. Restore @rq for + * normal completion and end it. + */ + BUG_ON(!list_empty(&rq->queuelist)); + list_del_init(&rq->flush.list); + blk_flush_restore_request(rq); + __blk_end_request_all(rq, error); + break; + + default: + BUG(); + } + + return blk_kick_flush(q) | queued; } -static void flush_data_end_io(struct request *rq, int error) +static void flush_end_io(struct request *flush_rq, int error) { - elv_completed_request(rq->q, rq); - blk_flush_complete_seq_end_io(rq->q, QUEUE_FSEQ_DATA, error); + struct request_queue *q = flush_rq->q; + struct list_head *running = &q->flush_queue[q->flush_running_idx]; + bool was_empty = elv_queue_empty(q); + bool queued = false; + struct request *rq, *n; + + BUG_ON(q->flush_pending_idx == q->flush_running_idx); + + /* account completion of the flush request */ + q->flush_running_idx ^= 1; + elv_completed_request(q, flush_rq); + + /* and push the waiting requests to the next stage */ + list_for_each_entry_safe(rq, n, running, flush.list) { + unsigned int seq = blk_flush_cur_seq(rq); + + BUG_ON(seq != REQ_FSEQ_PREFLUSH && seq != REQ_FSEQ_POSTFLUSH); + queued |= blk_flush_complete_seq(rq, seq, error); + } + + /* after populating an empty queue, kick it to avoid stall */ + if (queued && was_empty) + __blk_run_queue(q); } -static void post_flush_end_io(struct request *rq, int error) +/** + * blk_kick_flush - consider issuing flush request + * @q: request_queue being kicked + * + * Flush related states of @q have changed, consider issuing flush request. + * Please read the comment at the top of this file for more info. + * + * CONTEXT: + * spin_lock_irq(q->queue_lock) + * + * RETURNS: + * %true if flush was issued, %false otherwise. + */ +static bool blk_kick_flush(struct request_queue *q) { - elv_completed_request(rq->q, rq); - blk_flush_complete_seq_end_io(rq->q, QUEUE_FSEQ_POSTFLUSH, error); + struct list_head *pending = &q->flush_queue[q->flush_pending_idx]; + struct request *first_rq = + list_first_entry(pending, struct request, flush.list); + + /* C1 described at the top of this file */ + if (q->flush_pending_idx != q->flush_running_idx || list_empty(pending)) + return false; + + /* C2 and C3 */ + if (!list_empty(&q->flush_data_in_flight) && + time_before(jiffies, + q->flush_pending_since + FLUSH_PENDING_TIMEOUT)) + return false; + + /* + * Issue flush and toggle pending_idx. This makes pending_idx + * different from running_idx, which means flush is in flight. + */ + blk_rq_init(q, &q->flush_rq); + q->flush_rq.cmd_type = REQ_TYPE_FS; + q->flush_rq.cmd_flags = WRITE_FLUSH | REQ_FLUSH_SEQ; + q->flush_rq.rq_disk = first_rq->rq_disk; + q->flush_rq.end_io = flush_end_io; + + q->flush_pending_idx ^= 1; + elv_insert(q, &q->flush_rq, ELEVATOR_INSERT_FRONT); + return true; } -static void init_flush_request(struct request *rq, struct gendisk *disk) +static void flush_data_end_io(struct request *rq, int error) { - rq->cmd_type = REQ_TYPE_FS; - rq->cmd_flags = WRITE_FLUSH; - rq->rq_disk = disk; + struct request_queue *q = rq->q; + bool was_empty = elv_queue_empty(q); + + /* after populating an empty queue, kick it to avoid stall */ + if (blk_flush_complete_seq(rq, REQ_FSEQ_DATA, error) && was_empty) + __blk_run_queue(q); } -static struct request *queue_next_fseq(struct request_queue *q) +/** + * blk_insert_flush - insert a new FLUSH/FUA request + * @rq: request to insert + * + * To be called from elv_insert() for %ELEVATOR_INSERT_FLUSH insertions. + * @rq is being submitted. Analyze what needs to be done and put it on the + * right queue. + * + * CONTEXT: + * spin_lock_irq(q->queue_lock) + */ +void blk_insert_flush(struct request *rq) { - struct request *orig_rq = q->orig_flush_rq; - struct request *rq = &q->flush_rq; + struct request_queue *q = rq->q; + unsigned int fflags = q->flush_flags; /* may change, cache */ + unsigned int policy = blk_flush_policy(fflags, rq); - blk_rq_init(q, rq); + BUG_ON(rq->end_io); + BUG_ON(!rq->bio || rq->bio != rq->biotail); - switch (blk_flush_cur_seq(q)) { - case QUEUE_FSEQ_PREFLUSH: - init_flush_request(rq, orig_rq->rq_disk); - rq->end_io = pre_flush_end_io; - break; - case QUEUE_FSEQ_DATA: - init_request_from_bio(rq, orig_rq->bio); - /* - * orig_rq->rq_disk may be different from - * bio->bi_bdev->bd_disk if orig_rq got here through - * remapping drivers. Make sure rq->rq_disk points - * to the same one as orig_rq. - */ - rq->rq_disk = orig_rq->rq_disk; - rq->cmd_flags &= ~(REQ_FLUSH | REQ_FUA); - rq->cmd_flags |= orig_rq->cmd_flags & (REQ_FLUSH | REQ_FUA); - rq->end_io = flush_data_end_io; - break; - case QUEUE_FSEQ_POSTFLUSH: - init_flush_request(rq, orig_rq->rq_disk); - rq->end_io = post_flush_end_io; - break; - default: - BUG(); + /* + * @policy now records what operations need to be done. Adjust + * REQ_FLUSH and FUA for the driver. + */ + rq->cmd_flags &= ~REQ_FLUSH; + if (!(fflags & REQ_FUA)) + rq->cmd_flags &= ~REQ_FUA; + + /* + * If there's data but flush is not necessary, the request can be + * processed directly without going through flush machinery. Queue + * for normal execution. + */ + if ((policy & REQ_FSEQ_DATA) && + !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) { + list_add(&rq->queuelist, &q->queue_head); + return; } + /* + * @rq should go through flush machinery. Mark it part of flush + * sequence and submit for further processing. + */ + memset(&rq->flush, 0, sizeof(rq->flush)); + INIT_LIST_HEAD(&rq->flush.list); rq->cmd_flags |= REQ_FLUSH_SEQ; - elv_insert(q, rq, ELEVATOR_INSERT_FRONT); - return rq; + rq->end_io = flush_data_end_io; + + blk_flush_complete_seq(rq, REQ_FSEQ_ACTIONS & ~policy, 0); } -struct request *blk_do_flush(struct request_queue *q, struct request *rq) +/** + * blk_abort_flushes - @q is being aborted, abort flush requests + * @q: request_queue being aborted + * + * To be called from elv_abort_queue(). @q is being aborted. Prepare all + * FLUSH/FUA requests for abortion. + * + * CONTEXT: + * spin_lock_irq(q->queue_lock) + */ +void blk_abort_flushes(struct request_queue *q) { - unsigned int fflags = q->flush_flags; /* may change, cache it */ - bool has_flush = fflags & REQ_FLUSH, has_fua = fflags & REQ_FUA; - bool do_preflush = has_flush && (rq->cmd_flags & REQ_FLUSH); - bool do_postflush = has_flush && !has_fua && (rq->cmd_flags & REQ_FUA); - unsigned skip = 0; + struct request *rq, *n; + int i; /* - * Special case. If there's data but flush is not necessary, - * the request can be issued directly. - * - * Flush w/o data should be able to be issued directly too but - * currently some drivers assume that rq->bio contains - * non-zero data if it isn't NULL and empty FLUSH requests - * getting here usually have bio's without data. + * Requests in flight for data are already owned by the dispatch + * queue or the device driver. Just restore for normal completion. */ - if (blk_rq_sectors(rq) && !do_preflush && !do_postflush) { - rq->cmd_flags &= ~REQ_FLUSH; - if (!has_fua) - rq->cmd_flags &= ~REQ_FUA; - return rq; + list_for_each_entry_safe(rq, n, &q->flush_data_in_flight, flush.list) { + list_del_init(&rq->flush.list); + blk_flush_restore_request(rq); } /* - * Sequenced flushes can't be processed in parallel. If - * another one is already in progress, queue for later - * processing. + * We need to give away requests on flush queues. Restore for + * normal completion and put them on the dispatch queue. */ - if (q->flush_seq) { - list_move_tail(&rq->queuelist, &q->pending_flushes); - return NULL; + for (i = 0; i < ARRAY_SIZE(q->flush_queue); i++) { + list_for_each_entry_safe(rq, n, &q->flush_queue[i], + flush.list) { + list_del_init(&rq->flush.list); + blk_flush_restore_request(rq); + list_add_tail(&rq->queuelist, &q->queue_head); + } } - - /* - * Start a new flush sequence - */ - q->flush_err = 0; - q->flush_seq |= QUEUE_FSEQ_STARTED; - - /* adjust FLUSH/FUA of the original request and stash it away */ - rq->cmd_flags &= ~REQ_FLUSH; - if (!has_fua) - rq->cmd_flags &= ~REQ_FUA; - blk_dequeue_request(rq); - q->orig_flush_rq = rq; - - /* skip unneded sequences and return the first one */ - if (!do_preflush) - skip |= QUEUE_FSEQ_PREFLUSH; - if (!blk_rq_sectors(rq)) - skip |= QUEUE_FSEQ_DATA; - if (!do_postflush) - skip |= QUEUE_FSEQ_POSTFLUSH; - return blk_flush_complete_seq(q, skip, 0); } static void bio_end_flush(struct bio *bio, int err) diff --git a/block/blk.h b/block/blk.h index 9d2ee8f..284b500 100644 --- a/block/blk.h +++ b/block/blk.h @@ -51,21 +51,17 @@ static inline void blk_clear_rq_complete(struct request *rq) */ #define ELV_ON_HASH(rq) (!hlist_unhashed(&(rq)->hash)) -struct request *blk_do_flush(struct request_queue *q, struct request *rq); +void blk_insert_flush(struct request *rq); +void blk_abort_flushes(struct request_queue *q); static inline struct request *__elv_next_request(struct request_queue *q) { struct request *rq; while (1) { - while (!list_empty(&q->queue_head)) { + if (!list_empty(&q->queue_head)) { rq = list_entry_rq(q->queue_head.next); - if (!(rq->cmd_flags & (REQ_FLUSH | REQ_FUA)) || - (rq->cmd_flags & REQ_FLUSH_SEQ)) - return rq; - rq = blk_do_flush(q, rq); - if (rq) - return rq; + return rq; } if (!q->elevator->ops->elevator_dispatch_fn(q, 0)) diff --git a/block/elevator.c b/block/elevator.c index 2569512..270e097 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -673,6 +673,11 @@ void elv_insert(struct request_queue *q, struct request *rq, int where) q->elevator->ops->elevator_add_req_fn(q, rq); break; + case ELEVATOR_INSERT_FLUSH: + rq->cmd_flags |= REQ_SOFTBARRIER; + blk_insert_flush(rq); + break; + default: printk(KERN_ERR "%s: bad insertion point %d\n", __func__, where); @@ -785,6 +790,8 @@ void elv_abort_queue(struct request_queue *q) { struct request *rq; + blk_abort_flushes(q); + while (!list_empty(&q->queue_head)) { rq = list_entry_rq(q->queue_head.next); rq->cmd_flags |= REQ_QUIET; -- cgit v1.1 From 9d5a4e946ce5352f19400b6370f4cd8e72806278 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Fri, 11 Feb 2011 11:05:46 +0100 Subject: block: skip elevator data initialization for flush requests Skip elevator initialization for flush requests by passing priv=0 to blk_alloc_request() in get_request(). As such elv_set_request() is never called for flush requests. Signed-off-by: Mike Snitzer Signed-off-by: Jens Axboe --- block/blk-core.c | 29 +++++++++++++++++++++++++---- 1 file changed, 25 insertions(+), 4 deletions(-) (limited to 'block') diff --git a/block/blk-core.c b/block/blk-core.c index 0574609..ab4a7696 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -738,6 +738,25 @@ static void freed_request(struct request_queue *q, int sync, int priv) } /* + * Determine if elevator data should be initialized when allocating the + * request associated with @bio. + */ +static bool blk_rq_should_init_elevator(struct bio *bio) +{ + if (!bio) + return true; + + /* + * Flush requests do not use the elevator so skip initialization. + * This allows a request to share the flush and elevator data. + */ + if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) + return false; + + return true; +} + +/* * Get a free request, queue_lock must be held. * Returns NULL on failure, with queue_lock held. * Returns !NULL on success, with queue_lock *not held*. @@ -749,7 +768,7 @@ static struct request *get_request(struct request_queue *q, int rw_flags, struct request_list *rl = &q->rq; struct io_context *ioc = NULL; const bool is_sync = rw_is_sync(rw_flags) != 0; - int may_queue, priv; + int may_queue, priv = 0; may_queue = elv_may_queue(q, rw_flags); if (may_queue == ELV_MQUEUE_NO) @@ -793,9 +812,11 @@ static struct request *get_request(struct request_queue *q, int rw_flags, rl->count[is_sync]++; rl->starved[is_sync] = 0; - priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); - if (priv) - rl->elvpriv++; + if (blk_rq_should_init_elevator(bio)) { + priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); + if (priv) + rl->elvpriv++; + } if (blk_queue_io_stat(q)) rw_flags |= REQ_IO_STAT; -- cgit v1.1 From c186794dbb466b45cf40f942f2d09d6d5b4b0e42 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Fri, 11 Feb 2011 11:08:00 +0100 Subject: block: share request flush fields with elevator_private Flush requests are never put on the IO scheduler. Convert request structure's elevator_private* into an array and have the flush fields share a union with it. Reclaim the space lost in 'struct request' by moving 'completion_data' back in the union with 'rb_node'. Signed-off-by: Mike Snitzer Acked-by: Vivek Goyal Acked-by: Tejun Heo Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 18 +++++++++--------- block/elevator.c | 2 +- 2 files changed, 10 insertions(+), 10 deletions(-) (limited to 'block') diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 4cd59b0..968455c 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -54,9 +54,9 @@ static const int cfq_hist_divisor = 4; #define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8) #define RQ_CIC(rq) \ - ((struct cfq_io_context *) (rq)->elevator_private) -#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2) -#define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private3) + ((struct cfq_io_context *) (rq)->elevator_private[0]) +#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private[1]) +#define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private[2]) static struct kmem_cache *cfq_pool; static struct kmem_cache *cfq_ioc_pool; @@ -3589,12 +3589,12 @@ static void cfq_put_request(struct request *rq) put_io_context(RQ_CIC(rq)->ioc); - rq->elevator_private = NULL; - rq->elevator_private2 = NULL; + rq->elevator_private[0] = NULL; + rq->elevator_private[1] = NULL; /* Put down rq reference on cfqg */ cfq_put_cfqg(RQ_CFQG(rq)); - rq->elevator_private3 = NULL; + rq->elevator_private[2] = NULL; cfq_put_queue(cfqq); } @@ -3685,9 +3685,9 @@ new_queue: spin_unlock_irqrestore(q->queue_lock, flags); - rq->elevator_private = cic; - rq->elevator_private2 = cfqq; - rq->elevator_private3 = cfq_ref_get_cfqg(cfqq->cfqg); + rq->elevator_private[0] = cic; + rq->elevator_private[1] = cfqq; + rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg); return 0; queue_fail: diff --git a/block/elevator.c b/block/elevator.c index 270e097..f98e92e 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -764,7 +764,7 @@ int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) if (e->ops->elevator_set_req_fn) return e->ops->elevator_set_req_fn(q, rq, gfp_mask); - rq->elevator_private = NULL; + rq->elevator_private[0] = NULL; return 0; } -- cgit v1.1 From 0bbfeb8320421989d3e12bd95fae86b9ac0712aa Mon Sep 17 00:00:00 2001 From: Justin TerAvest Date: Tue, 1 Mar 2011 15:05:08 -0500 Subject: cfq-iosched: Always provide group isolation. Effectively, make group_isolation=1 the default and remove the tunable. The setting group_isolation=0 was because by default we idle on sync-noidle tree and on fast devices, this can be very harmful for throughput. However, this problem can also be addressed by tuning slice_idle and possibly group_idle on faster storage devices. This change simplifies the CFQ code by removing the feature entirely. Signed-off-by: Justin TerAvest Acked-by: Vivek Goyal Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 37 +------------------------------------ 1 file changed, 1 insertion(+), 36 deletions(-) (limited to 'block') diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index f27ff3e..3202c7e 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -146,7 +146,6 @@ struct cfq_queue { struct cfq_rb_root *service_tree; struct cfq_queue *new_cfqq; struct cfq_group *cfqg; - struct cfq_group *orig_cfqg; /* Number of sectors dispatched from queue in single dispatch round */ unsigned long nr_sectors; }; @@ -285,7 +284,6 @@ struct cfq_data { unsigned int cfq_slice_idle; unsigned int cfq_group_idle; unsigned int cfq_latency; - unsigned int cfq_group_isolation; unsigned int cic_index; struct list_head cic_list; @@ -1187,32 +1185,6 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, int new_cfqq = 1; int group_changed = 0; -#ifdef CONFIG_CFQ_GROUP_IOSCHED - if (!cfqd->cfq_group_isolation - && cfqq_type(cfqq) == SYNC_NOIDLE_WORKLOAD - && cfqq->cfqg && cfqq->cfqg != &cfqd->root_group) { - /* Move this cfq to root group */ - cfq_log_cfqq(cfqd, cfqq, "moving to root group"); - if (!RB_EMPTY_NODE(&cfqq->rb_node)) - cfq_group_service_tree_del(cfqd, cfqq->cfqg); - cfqq->orig_cfqg = cfqq->cfqg; - cfqq->cfqg = &cfqd->root_group; - cfqd->root_group.ref++; - group_changed = 1; - } else if (!cfqd->cfq_group_isolation - && cfqq_type(cfqq) == SYNC_WORKLOAD && cfqq->orig_cfqg) { - /* cfqq is sequential now needs to go to its original group */ - BUG_ON(cfqq->cfqg != &cfqd->root_group); - if (!RB_EMPTY_NODE(&cfqq->rb_node)) - cfq_group_service_tree_del(cfqd, cfqq->cfqg); - cfq_put_cfqg(cfqq->cfqg); - cfqq->cfqg = cfqq->orig_cfqg; - cfqq->orig_cfqg = NULL; - group_changed = 1; - cfq_log_cfqq(cfqd, cfqq, "moved to origin group"); - } -#endif - service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq), cfqq_type(cfqq)); if (cfq_class_idle(cfqq)) { @@ -2542,7 +2514,7 @@ static int cfq_dispatch_requests(struct request_queue *q, int force) static void cfq_put_queue(struct cfq_queue *cfqq) { struct cfq_data *cfqd = cfqq->cfqd; - struct cfq_group *cfqg, *orig_cfqg; + struct cfq_group *cfqg; BUG_ON(cfqq->ref <= 0); @@ -2554,7 +2526,6 @@ static void cfq_put_queue(struct cfq_queue *cfqq) BUG_ON(rb_first(&cfqq->sort_list)); BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); cfqg = cfqq->cfqg; - orig_cfqg = cfqq->orig_cfqg; if (unlikely(cfqd->active_queue == cfqq)) { __cfq_slice_expired(cfqd, cfqq, 0); @@ -2564,8 +2535,6 @@ static void cfq_put_queue(struct cfq_queue *cfqq) BUG_ON(cfq_cfqq_on_rr(cfqq)); kmem_cache_free(cfq_pool, cfqq); cfq_put_cfqg(cfqg); - if (orig_cfqg) - cfq_put_cfqg(orig_cfqg); } /* @@ -3953,7 +3922,6 @@ static void *cfq_init_queue(struct request_queue *q) cfqd->cfq_slice_idle = cfq_slice_idle; cfqd->cfq_group_idle = cfq_group_idle; cfqd->cfq_latency = 1; - cfqd->cfq_group_isolation = 0; cfqd->hw_tag = -1; /* * we optimistically start assuming sync ops weren't delayed in last @@ -4029,7 +3997,6 @@ SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0); -SHOW_FUNCTION(cfq_group_isolation_show, cfqd->cfq_group_isolation, 0); #undef SHOW_FUNCTION #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ @@ -4063,7 +4030,6 @@ STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, UINT_MAX, 0); STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0); -STORE_FUNCTION(cfq_group_isolation_store, &cfqd->cfq_group_isolation, 0, 1, 0); #undef STORE_FUNCTION #define CFQ_ATTR(name) \ @@ -4081,7 +4047,6 @@ static struct elv_fs_entry cfq_attrs[] = { CFQ_ATTR(slice_idle), CFQ_ATTR(group_idle), CFQ_ATTR(low_latency), - CFQ_ATTR(group_isolation), __ATTR_NULL }; -- cgit v1.1 From 53f22956effe1c9e7961b8c6e4362ecca5e460b7 Mon Sep 17 00:00:00 2001 From: Liu Yuan Date: Wed, 2 Mar 2011 11:00:15 -0500 Subject: block/genhd: Change some numerals into macros Rename the numerals in the diskstats_show() into the macros. Cc: Jens Axboe Signed-off-by: Liu Yuan Signed-off-by: Jens Axboe --- block/genhd.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) (limited to 'block') diff --git a/block/genhd.c b/block/genhd.c index 6a5b772..73d85a8 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -1158,14 +1158,14 @@ static int diskstats_show(struct seq_file *seqf, void *v) "%u %lu %lu %llu %u %u %u %u\n", MAJOR(part_devt(hd)), MINOR(part_devt(hd)), disk_name(gp, hd->partno, buf), - part_stat_read(hd, ios[0]), - part_stat_read(hd, merges[0]), - (unsigned long long)part_stat_read(hd, sectors[0]), - jiffies_to_msecs(part_stat_read(hd, ticks[0])), - part_stat_read(hd, ios[1]), - part_stat_read(hd, merges[1]), - (unsigned long long)part_stat_read(hd, sectors[1]), - jiffies_to_msecs(part_stat_read(hd, ticks[1])), + part_stat_read(hd, ios[READ]), + part_stat_read(hd, merges[READ]), + (unsigned long long)part_stat_read(hd, sectors[READ]), + jiffies_to_msecs(part_stat_read(hd, ticks[READ])), + part_stat_read(hd, ios[WRITE]), + part_stat_read(hd, merges[WRITE]), + (unsigned long long)part_stat_read(hd, sectors[WRITE]), + jiffies_to_msecs(part_stat_read(hd, ticks[WRITE])), part_in_flight(hd), jiffies_to_msecs(part_stat_read(hd, io_ticks)), jiffies_to_msecs(part_stat_read(hd, time_in_queue)) -- cgit v1.1 From c94a96ac93b4f5b8d1ff8430b1afa1a25610cf53 Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Wed, 2 Mar 2011 19:04:42 -0500 Subject: block: Initialize ->queue_lock to internal lock at queue allocation time There does not seem to be a clear convention whether q->queue_lock is initialized or not when blk_cleanup_queue() is called. In the past it was not necessary but now blk_throtl_exit() takes up queue lock by default and needs queue lock to be available. In fact elevator_exit() code also has similar requirement just that it is less stringent in the sense that elevator_exit() is called only if elevator is initialized. Two problems have been noticed because of ambiguity about spin lock status. - If a driver calls blk_alloc_queue() and then soon calls blk_cleanup_queue() almost immediately, (because some other driver structure allocation failed or some other error happened) then blk_throtl_exit() will run into issues as queue lock is not initialized. Loop driver ran into this issue recently and I noticed error paths in md driver too. Similar error paths should exist in other drivers too. - If some driver provided external spin lock and zapped the lock before blk_cleanup_queue(), then it can lead to issues. So this patch initializes the default queue lock at queue allocation time. block throttling code is one of the users of queue lock and it is initialized at the queue allocation time, so it makes sense to initialize ->queue_lock also to internal lock. A driver can overide that lock later. This will take care of the issue where a driver does not have to worry about initializing the queue lock to default before calling blk_cleanup_queue() Signed-off-by: Vivek Goyal Signed-off-by: Jens Axboe --- block/blk-core.c | 16 +++++++++++++++- block/blk-settings.c | 7 ------- 2 files changed, 15 insertions(+), 8 deletions(-) (limited to 'block') diff --git a/block/blk-core.c b/block/blk-core.c index 3cc17e60..bc2b7c5 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -446,6 +446,11 @@ void blk_put_queue(struct request_queue *q) kobject_put(&q->kobj); } +/* + * Note: If a driver supplied the queue lock, it should not zap that lock + * unexpectedly as some queue cleanup components like elevator_exit() and + * blk_throtl_exit() need queue lock. + */ void blk_cleanup_queue(struct request_queue *q) { /* @@ -540,6 +545,12 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) mutex_init(&q->sysfs_lock); spin_lock_init(&q->__queue_lock); + /* + * By default initialize queue_lock to internal lock and driver can + * override it later if need be. + */ + q->queue_lock = &q->__queue_lock; + return q; } EXPORT_SYMBOL(blk_alloc_queue_node); @@ -624,7 +635,10 @@ blk_init_allocated_queue_node(struct request_queue *q, request_fn_proc *rfn, q->unprep_rq_fn = NULL; q->unplug_fn = generic_unplug_device; q->queue_flags = QUEUE_FLAG_DEFAULT; - q->queue_lock = lock; + + /* Override internal queue lock with supplied lock pointer */ + if (lock) + q->queue_lock = lock; /* * This also sets hw/phys segments, boundary and size diff --git a/block/blk-settings.c b/block/blk-settings.c index 36c8c1f..df649fa 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -176,13 +176,6 @@ void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn) blk_queue_max_hw_sectors(q, BLK_SAFE_MAX_SECTORS); /* - * If the caller didn't supply a lock, fall back to our embedded - * per-queue locks - */ - if (!q->queue_lock) - q->queue_lock = &q->__queue_lock; - - /* * by default assume old behaviour and bounce for any highmem page */ blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH); -- cgit v1.1 From da527770007fce8e4541947d47918248286da875 Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Wed, 2 Mar 2011 19:05:33 -0500 Subject: block: Move blk_throtl_exit() call to blk_cleanup_queue() Move blk_throtl_exit() in blk_cleanup_queue() as blk_throtl_exit() is written in such a way that it needs queue lock. In blk_release_queue() there is no gurantee that ->queue_lock is still around. Initially blk_throtl_exit() was in blk_cleanup_queue() but Ingo reported one problem. https://lkml.org/lkml/2010/10/23/86 And a quick fix moved blk_throtl_exit() to blk_release_queue(). commit 7ad58c028652753814054f4e3ac58f925e7343f4 Author: Jens Axboe Date: Sat Oct 23 20:40:26 2010 +0200 block: fix use-after-free bug in blk throttle code This patch reverts above change and does not try to shutdown the throtl work in blk_sync_queue(). By avoiding call to throtl_shutdown_timer_wq() from blk_sync_queue(), we should also avoid the problem reported by Ingo. blk_sync_queue() seems to be used only by md driver and it seems to be using it to make sure q->unplug_fn is not called as md registers its own unplug functions and it is about to free up the data structures used by unplug_fn(). Block throttle does not call back into unplug_fn() or into md. So there is no need to cancel blk throttle work. In fact I think cancelling block throttle work is bad because it might happen that some bios are throttled and scheduled to be dispatched later with the help of pending work and if work is cancelled, these bios might never be dispatched. Block layer also uses blk_sync_queue() during blk_cleanup_queue() and blk_release_queue() time. That should be safe as we are also calling blk_throtl_exit() which should make sure all the throttling related data structures are cleaned up. Signed-off-by: Vivek Goyal Signed-off-by: Jens Axboe --- block/blk-core.c | 7 ++++++- block/blk-sysfs.c | 2 -- block/blk-throttle.c | 6 +++--- 3 files changed, 9 insertions(+), 6 deletions(-) (limited to 'block') diff --git a/block/blk-core.c b/block/blk-core.c index bc2b7c5..accff29 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -380,13 +380,16 @@ EXPORT_SYMBOL(blk_stop_queue); * that its ->make_request_fn will not re-add plugging prior to calling * this function. * + * This function does not cancel any asynchronous activity arising + * out of elevator or throttling code. That would require elevaotor_exit() + * and blk_throtl_exit() to be called with queue lock initialized. + * */ void blk_sync_queue(struct request_queue *q) { del_timer_sync(&q->unplug_timer); del_timer_sync(&q->timeout); cancel_work_sync(&q->unplug_work); - throtl_shutdown_timer_wq(q); } EXPORT_SYMBOL(blk_sync_queue); @@ -469,6 +472,8 @@ void blk_cleanup_queue(struct request_queue *q) if (q->elevator) elevator_exit(q->elevator); + blk_throtl_exit(q); + blk_put_queue(q); } EXPORT_SYMBOL(blk_cleanup_queue); diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index 41fb691..261c75c 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -471,8 +471,6 @@ static void blk_release_queue(struct kobject *kobj) blk_sync_queue(q); - blk_throtl_exit(q); - if (rl->rq_pool) mempool_destroy(rl->rq_pool); diff --git a/block/blk-throttle.c b/block/blk-throttle.c index a89043a..c0f6237 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -965,7 +965,7 @@ static void throtl_update_blkio_group_write_iops(void *key, throtl_schedule_delayed_work(td->queue, 0); } -void throtl_shutdown_timer_wq(struct request_queue *q) +static void throtl_shutdown_wq(struct request_queue *q) { struct throtl_data *td = q->td; @@ -1099,7 +1099,7 @@ void blk_throtl_exit(struct request_queue *q) BUG_ON(!td); - throtl_shutdown_timer_wq(q); + throtl_shutdown_wq(q); spin_lock_irq(q->queue_lock); throtl_release_tgs(td); @@ -1129,7 +1129,7 @@ void blk_throtl_exit(struct request_queue *q) * update limits through cgroup and another work got queued, cancel * it. */ - throtl_shutdown_timer_wq(q); + throtl_shutdown_wq(q); throtl_td_free(td); } -- cgit v1.1 From 93803e0140c6216b68fe926ccc611297120da273 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Mon, 7 Mar 2011 08:59:06 +0100 Subject: cfq-iosched: fix race in cfq_set_request() We need to hold the queue lock over the reference increment, it's not atomic anymore. Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'block') diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 3202c7e..fb2141e 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -3675,12 +3675,11 @@ new_queue: cfqq->allocated[rw]++; - spin_unlock_irqrestore(q->queue_lock, flags); - cfqq->ref++; rq->elevator_private[0] = cic; rq->elevator_private[1] = cfqq; rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg); + spin_unlock_irqrestore(q->queue_lock, flags); return 0; queue_fail: -- cgit v1.1 From ef8a41df8c140f10108de75b01b6369d6e49113c Mon Sep 17 00:00:00 2001 From: Shaohua Li Date: Mon, 7 Mar 2011 09:26:29 +0100 Subject: cfq-iosched: give busy sync queue no dispatch limit If there are a sync and an async queue and the sync queue's think time is small, we can ignore the sync queue's dispatch quantum. Because the sync queue will always preempt the async queue, we don't need to care about async's latency. This can fix a performance regression of aiostress test, which is introduced by commit f8ae6e3eb825. The issue should exist even without the commit, but the commit amplifies the impact. The initial post does the same optimization for RT queue too, but since I have no real workload for it, Vivek suggests to drop it. Signed-off-by: Shaohua Li Reviewed-by: Gui Jianfeng Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 26 ++++++++++++++++++++++++-- 1 file changed, 24 insertions(+), 2 deletions(-) (limited to 'block') diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index fb2141e..135b1a4 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -237,6 +237,7 @@ struct cfq_data { struct rb_root prio_trees[CFQ_PRIO_LISTS]; unsigned int busy_queues; + unsigned int busy_sync_queues; int rq_in_driver; int rq_in_flight[2]; @@ -1344,6 +1345,8 @@ static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) BUG_ON(cfq_cfqq_on_rr(cfqq)); cfq_mark_cfqq_on_rr(cfqq); cfqd->busy_queues++; + if (cfq_cfqq_sync(cfqq)) + cfqd->busy_sync_queues++; cfq_resort_rr_list(cfqd, cfqq); } @@ -1370,6 +1373,8 @@ static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) cfq_group_service_tree_del(cfqd, cfqq->cfqg); BUG_ON(!cfqd->busy_queues); cfqd->busy_queues--; + if (cfq_cfqq_sync(cfqq)) + cfqd->busy_sync_queues--; } /* @@ -2377,6 +2382,7 @@ static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) * Does this cfqq already have too much IO in flight? */ if (cfqq->dispatched >= max_dispatch) { + bool promote_sync = false; /* * idle queue must always only have a single IO in flight */ @@ -2384,15 +2390,31 @@ static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) return false; /* + * If there is only one sync queue, and its think time is + * small, we can ignore async queue here and give the sync + * queue no dispatch limit. The reason is a sync queue can + * preempt async queue, limiting the sync queue doesn't make + * sense. This is useful for aiostress test. + */ + if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1) { + struct cfq_io_context *cic = RQ_CIC(cfqq->next_rq); + + if (sample_valid(cic->ttime_samples) && + cic->ttime_mean < cfqd->cfq_slice_idle) + promote_sync = true; + } + + /* * We have other queues, don't allow more IO from this one */ - if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq)) + if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) && + !promote_sync) return false; /* * Sole queue user, no limit */ - if (cfqd->busy_queues == 1) + if (cfqd->busy_queues == 1 || promote_sync) max_dispatch = -1; else /* -- cgit v1.1 From a60327107b56573c305ecc78e471dbdbb4d2f426 Mon Sep 17 00:00:00 2001 From: Gui Jianfeng Date: Mon, 7 Mar 2011 09:28:09 +0100 Subject: cfq-iosched: Fix update_vdisktime logic The update_vdisktime logic is broken since commit b54ce60eb7f61f8e314b8b241b0469eda3bb1d42, st->min_vdisktime never makes a progress. Fix it. Thanks Vivek for pointing it out. Signed-off-by: Gui Jianfeng Acked-by: Vivek Goyal Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'block') diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 135b1a4..938ae52 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -557,15 +557,13 @@ static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime) static void update_min_vdisktime(struct cfq_rb_root *st) { - u64 vdisktime = st->min_vdisktime; struct cfq_group *cfqg; if (st->left) { cfqg = rb_entry_cfqg(st->left); - vdisktime = min_vdisktime(vdisktime, cfqg->vdisktime); + st->min_vdisktime = max_vdisktime(st->min_vdisktime, + cfqg->vdisktime); } - - st->min_vdisktime = max_vdisktime(st->min_vdisktime, vdisktime); } /* -- cgit v1.1 From 231d704b4ab7491473c0b1a9cd0c6e0d1cba85b9 Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Mon, 7 Mar 2011 21:05:14 +0100 Subject: blk-throttle: process limit change only through one function With the help of cgroup interface one can go and upate the bps/iops limits of existing group. Once the limits are udpated, a thread is woken up to see if some blocked group needs recalculation based on new limits and needs to be requeued. There was also a piece of code where I was checking for group limit update when a fresh bio comes in. This patch gets rid of that piece of code and keeps processing the limit change at one place throtl_process_limit_change(). It just keeps the code simple and easy to understand. Signed-off-by: Vivek Goyal Signed-off-by: Jens Axboe --- block/blk-throttle.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) (limited to 'block') diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 061dee6..a29f092 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -1009,14 +1009,8 @@ int blk_throtl_bio(struct request_queue *q, struct bio **biop) /* * There is already another bio queued in same dir. No * need to update dispatch time. - * Still update the disptime if rate limits on this group - * were changed. */ - if (!tg->limits_changed) - update_disptime = false; - else - tg->limits_changed = false; - + update_disptime = false; goto queue_bio; } -- cgit v1.1 From de701c74a34005e637e1ca2634fbf28fd1debba2 Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Mon, 7 Mar 2011 21:09:32 +0100 Subject: blk-throttle: Some cleanups and race fixes in limit update code When throttle group limits are updated through cgroups, a thread is woken up to process these updates. While reviewing that code, oleg noted couple of race conditions existed in the code and he also suggested that code can be simplified. This patch fixes the races simplifies the code based on Oleg's suggestions: - Use xchg(). - Introduced a common function throtl_update_blkio_group_common() which is shared now by all iops/bps update functions. Reviewed-by: Oleg Nesterov Reviewed-by: Paul E. McKenney Signed-off-by: Vivek Goyal Fixed a merge issue, throtl_schedule_delayed_work() takes throtl_data as the argument now, not the queue. Signed-off-by: Jens Axboe --- block/blk-throttle.c | 96 ++++++++++++++++++++++------------------------------ 1 file changed, 40 insertions(+), 56 deletions(-) (limited to 'block') diff --git a/block/blk-throttle.c b/block/blk-throttle.c index a29f092..32dd3e4 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -102,7 +102,7 @@ struct throtl_data /* Work for dispatching throttled bios */ struct delayed_work throtl_work; - atomic_t limits_changed; + bool limits_changed; }; enum tg_state_flags { @@ -201,6 +201,7 @@ static struct throtl_grp * throtl_find_alloc_tg(struct throtl_data *td, RB_CLEAR_NODE(&tg->rb_node); bio_list_init(&tg->bio_lists[0]); bio_list_init(&tg->bio_lists[1]); + td->limits_changed = false; /* * Take the initial reference that will be released on destroy @@ -737,34 +738,27 @@ static void throtl_process_limit_change(struct throtl_data *td) struct throtl_grp *tg; struct hlist_node *pos, *n; - if (!atomic_read(&td->limits_changed)) + if (!td->limits_changed) return; - throtl_log(td, "limit changed =%d", atomic_read(&td->limits_changed)); + xchg(&td->limits_changed, false); - /* - * Make sure updates from throtl_update_blkio_group_read_bps() group - * of functions to tg->limits_changed are visible. We do not - * want update td->limits_changed to be visible but update to - * tg->limits_changed not being visible yet on this cpu. Hence - * the read barrier. - */ - smp_rmb(); + throtl_log(td, "limits changed"); hlist_for_each_entry_safe(tg, pos, n, &td->tg_list, tg_node) { - if (throtl_tg_on_rr(tg) && tg->limits_changed) { - throtl_log_tg(td, tg, "limit change rbps=%llu wbps=%llu" - " riops=%u wiops=%u", tg->bps[READ], - tg->bps[WRITE], tg->iops[READ], - tg->iops[WRITE]); + if (!tg->limits_changed) + continue; + + if (!xchg(&tg->limits_changed, false)) + continue; + + throtl_log_tg(td, tg, "limit change rbps=%llu wbps=%llu" + " riops=%u wiops=%u", tg->bps[READ], tg->bps[WRITE], + tg->iops[READ], tg->iops[WRITE]); + + if (throtl_tg_on_rr(tg)) tg_update_disptime(td, tg); - tg->limits_changed = false; - } } - - smp_mb__before_atomic_dec(); - atomic_dec(&td->limits_changed); - smp_mb__after_atomic_dec(); } /* Dispatch throttled bios. Should be called without queue lock held. */ @@ -898,6 +892,15 @@ void throtl_unlink_blkio_group(void *key, struct blkio_group *blkg) spin_unlock_irqrestore(td->queue->queue_lock, flags); } +static void throtl_update_blkio_group_common(struct throtl_data *td, + struct throtl_grp *tg) +{ + xchg(&tg->limits_changed, true); + xchg(&td->limits_changed, true); + /* Schedule a work now to process the limit change */ + throtl_schedule_delayed_work(td, 0); +} + /* * For all update functions, key should be a valid pointer because these * update functions are called under blkcg_lock, that means, blkg is @@ -911,61 +914,40 @@ static void throtl_update_blkio_group_read_bps(void *key, struct blkio_group *blkg, u64 read_bps) { struct throtl_data *td = key; + struct throtl_grp *tg = tg_of_blkg(blkg); - tg_of_blkg(blkg)->bps[READ] = read_bps; - /* Make sure read_bps is updated before setting limits_changed */ - smp_wmb(); - tg_of_blkg(blkg)->limits_changed = true; - - /* Make sure tg->limits_changed is updated before td->limits_changed */ - smp_mb__before_atomic_inc(); - atomic_inc(&td->limits_changed); - smp_mb__after_atomic_inc(); - - /* Schedule a work now to process the limit change */ - throtl_schedule_delayed_work(td, 0); + tg->bps[READ] = read_bps; + throtl_update_blkio_group_common(td, tg); } static void throtl_update_blkio_group_write_bps(void *key, struct blkio_group *blkg, u64 write_bps) { struct throtl_data *td = key; + struct throtl_grp *tg = tg_of_blkg(blkg); - tg_of_blkg(blkg)->bps[WRITE] = write_bps; - smp_wmb(); - tg_of_blkg(blkg)->limits_changed = true; - smp_mb__before_atomic_inc(); - atomic_inc(&td->limits_changed); - smp_mb__after_atomic_inc(); - throtl_schedule_delayed_work(td, 0); + tg->bps[WRITE] = write_bps; + throtl_update_blkio_group_common(td, tg); } static void throtl_update_blkio_group_read_iops(void *key, struct blkio_group *blkg, unsigned int read_iops) { struct throtl_data *td = key; + struct throtl_grp *tg = tg_of_blkg(blkg); - tg_of_blkg(blkg)->iops[READ] = read_iops; - smp_wmb(); - tg_of_blkg(blkg)->limits_changed = true; - smp_mb__before_atomic_inc(); - atomic_inc(&td->limits_changed); - smp_mb__after_atomic_inc(); - throtl_schedule_delayed_work(td, 0); + tg->iops[READ] = read_iops; + throtl_update_blkio_group_common(td, tg); } static void throtl_update_blkio_group_write_iops(void *key, struct blkio_group *blkg, unsigned int write_iops) { struct throtl_data *td = key; + struct throtl_grp *tg = tg_of_blkg(blkg); - tg_of_blkg(blkg)->iops[WRITE] = write_iops; - smp_wmb(); - tg_of_blkg(blkg)->limits_changed = true; - smp_mb__before_atomic_inc(); - atomic_inc(&td->limits_changed); - smp_mb__after_atomic_inc(); - throtl_schedule_delayed_work(td, 0); + tg->iops[WRITE] = write_iops; + throtl_update_blkio_group_common(td, tg); } static void throtl_shutdown_wq(struct request_queue *q) @@ -1012,6 +994,7 @@ int blk_throtl_bio(struct request_queue *q, struct bio **biop) */ update_disptime = false; goto queue_bio; + } /* Bio is with-in rate limit of group */ @@ -1052,7 +1035,7 @@ int blk_throtl_init(struct request_queue *q) INIT_HLIST_HEAD(&td->tg_list); td->tg_service_tree = THROTL_RB_ROOT; - atomic_set(&td->limits_changed, 0); + td->limits_changed = false; /* Init root group */ tg = &td->root_tg; @@ -1064,6 +1047,7 @@ int blk_throtl_init(struct request_queue *q) /* Practically unlimited BW */ tg->bps[0] = tg->bps[1] = -1; tg->iops[0] = tg->iops[1] = -1; + td->limits_changed = false; /* * Set root group reference to 2. One reference will be dropped when -- cgit v1.1 From df457f845e5449be2e7d96668791f789b3770ac7 Mon Sep 17 00:00:00 2001 From: Justin TerAvest Date: Tue, 8 Mar 2011 19:45:00 +0100 Subject: blk-cgroup: Lower minimum weight from 100 to 10. We've found that we still get good, useful isolation at weights this low. I'd like to adjust the minimum so that any other changes can take these values into account. Signed-off-by: Justin TerAvest Acked-by: Vivek Goyal Signed-off-by: Jens Axboe --- block/blk-cgroup.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'block') diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h index ea4861b..57e7234 100644 --- a/block/blk-cgroup.h +++ b/block/blk-cgroup.h @@ -240,7 +240,7 @@ static inline char *blkg_path(struct blkio_group *blkg) { return NULL; } #endif -#define BLKIO_WEIGHT_MIN 100 +#define BLKIO_WEIGHT_MIN 10 #define BLKIO_WEIGHT_MAX 1000 #define BLKIO_WEIGHT_DEFAULT 500 -- cgit v1.1 From facc31ddc3570a3a0d8951c94f16b898e01b464d Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 9 Mar 2011 19:54:27 +0100 Subject: block: Don't implicitly trigger event check on disk_unblock_events() Currently, disk_unblock_events() implicitly kick event check if the block count reaches zero. This behavior is not described in the comment and hinders with future changes. Make the unblocker explicitly check events by calling disk_check_events() as necessary. This patch doesn't cause any behavior difference. Signed-off-by: Tejun Heo Cc: Jens Axboe Cc: Kay Sievers --- block/genhd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'block') diff --git a/block/genhd.c b/block/genhd.c index 3e2b57b..c91a2da 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -1494,7 +1494,7 @@ void disk_block_events(struct gendisk *disk) void disk_unblock_events(struct gendisk *disk) { if (disk->ev) - __disk_unblock_events(disk, true); + __disk_unblock_events(disk, false); } /** -- cgit v1.1 From 3cca6dc1c81e2407928dc4c6105252146fd3924f Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 2 Mar 2011 11:08:00 -0500 Subject: block: add API for delaying work/request_fn a little bit Currently we use plugging for that, but as plugging is going away, we need an alternative mechanism. Signed-off-by: Jens Axboe --- block/blk-core.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) (limited to 'block') diff --git a/block/blk-core.c b/block/blk-core.c index 3cc17e60..e958c7a 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -197,6 +197,32 @@ void blk_dump_rq_flags(struct request *rq, char *msg) } EXPORT_SYMBOL(blk_dump_rq_flags); +static void blk_delay_work(struct work_struct *work) +{ + struct request_queue *q; + + q = container_of(work, struct request_queue, delay_work.work); + spin_lock_irq(q->queue_lock); + q->request_fn(q); + spin_unlock_irq(q->queue_lock); +} + +/** + * blk_delay_queue - restart queueing after defined interval + * @q: The &struct request_queue in question + * @msecs: Delay in msecs + * + * Description: + * Sometimes queueing needs to be postponed for a little while, to allow + * resources to come back. This function will make sure that queueing is + * restarted around the specified time. + */ +void blk_delay_queue(struct request_queue *q, unsigned long msecs) +{ + schedule_delayed_work(&q->delay_work, msecs_to_jiffies(msecs)); +} +EXPORT_SYMBOL(blk_delay_queue); + /* * "plug" the device if there are no outstanding requests: this will * force the transfer to start only after we have put all the requests @@ -363,6 +389,7 @@ EXPORT_SYMBOL(blk_start_queue); void blk_stop_queue(struct request_queue *q) { blk_remove_plug(q); + cancel_delayed_work(&q->delay_work); queue_flag_set(QUEUE_FLAG_STOPPED, q); } EXPORT_SYMBOL(blk_stop_queue); @@ -387,6 +414,7 @@ void blk_sync_queue(struct request_queue *q) del_timer_sync(&q->timeout); cancel_work_sync(&q->unplug_work); throtl_shutdown_timer_wq(q); + cancel_delayed_work_sync(&q->delay_work); } EXPORT_SYMBOL(blk_sync_queue); @@ -534,6 +562,7 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) INIT_LIST_HEAD(&q->flush_queue[1]); INIT_LIST_HEAD(&q->flush_data_in_flight); INIT_WORK(&q->unplug_work, blk_unplug_work); + INIT_DELAYED_WORK(&q->delay_work, blk_delay_work); kobject_init(&q->kobj, &blk_queue_ktype); -- cgit v1.1 From 73c101011926c5832e6e141682180c4debe2cf45 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 8 Mar 2011 13:19:51 +0100 Subject: block: initial patch for on-stack per-task plugging This patch adds support for creating a queuing context outside of the queue itself. This enables us to batch up pieces of IO before grabbing the block device queue lock and submitting them to the IO scheduler. The context is created on the stack of the process and assigned in the task structure, so that we can auto-unplug it if we hit a schedule event. The current queue plugging happens implicitly if IO is submitted to an empty device, yet callers have to remember to unplug that IO when they are going to wait for it. This is an ugly API and has caused bugs in the past. Additionally, it requires hacks in the vm (->sync_page() callback) to handle that logic. By switching to an explicit plugging scheme we make the API a lot nicer and can get rid of the ->sync_page() hack in the vm. Signed-off-by: Jens Axboe --- block/blk-core.c | 369 +++++++++++++++++++++++++++++++++++++++--------------- block/blk-flush.c | 3 +- block/elevator.c | 6 +- 3 files changed, 277 insertions(+), 101 deletions(-) (limited to 'block') diff --git a/block/blk-core.c b/block/blk-core.c index e958c7a..6efb55c 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -27,6 +27,7 @@ #include #include #include +#include #define CREATE_TRACE_POINTS #include @@ -203,7 +204,7 @@ static void blk_delay_work(struct work_struct *work) q = container_of(work, struct request_queue, delay_work.work); spin_lock_irq(q->queue_lock); - q->request_fn(q); + __blk_run_queue(q); spin_unlock_irq(q->queue_lock); } @@ -686,6 +687,8 @@ int blk_get_queue(struct request_queue *q) static inline void blk_free_request(struct request_queue *q, struct request *rq) { + BUG_ON(rq->cmd_flags & REQ_ON_PLUG); + if (rq->cmd_flags & REQ_ELVPRIV) elv_put_request(q, rq); mempool_free(rq, q->rq.rq_pool); @@ -1051,6 +1054,13 @@ void blk_requeue_request(struct request_queue *q, struct request *rq) } EXPORT_SYMBOL(blk_requeue_request); +static void add_acct_request(struct request_queue *q, struct request *rq, + int where) +{ + drive_stat_acct(rq, 1); + __elv_add_request(q, rq, where, 0); +} + /** * blk_insert_request - insert a special request into a request queue * @q: request queue where request should be inserted @@ -1093,8 +1103,7 @@ void blk_insert_request(struct request_queue *q, struct request *rq, if (blk_rq_tagged(rq)) blk_queue_end_tag(q, rq); - drive_stat_acct(rq, 1); - __elv_add_request(q, rq, where, 0); + add_acct_request(q, rq, where); __blk_run_queue(q); spin_unlock_irqrestore(q->queue_lock, flags); } @@ -1215,6 +1224,113 @@ void blk_add_request_payload(struct request *rq, struct page *page, } EXPORT_SYMBOL_GPL(blk_add_request_payload); +static bool bio_attempt_back_merge(struct request_queue *q, struct request *req, + struct bio *bio) +{ + const int ff = bio->bi_rw & REQ_FAILFAST_MASK; + + /* + * Debug stuff, kill later + */ + if (!rq_mergeable(req)) { + blk_dump_rq_flags(req, "back"); + return false; + } + + if (!ll_back_merge_fn(q, req, bio)) + return false; + + trace_block_bio_backmerge(q, bio); + + if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) + blk_rq_set_mixed_merge(req); + + req->biotail->bi_next = bio; + req->biotail = bio; + req->__data_len += bio->bi_size; + req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); + + drive_stat_acct(req, 0); + return true; +} + +static bool bio_attempt_front_merge(struct request_queue *q, + struct request *req, struct bio *bio) +{ + const int ff = bio->bi_rw & REQ_FAILFAST_MASK; + sector_t sector; + + /* + * Debug stuff, kill later + */ + if (!rq_mergeable(req)) { + blk_dump_rq_flags(req, "front"); + return false; + } + + if (!ll_front_merge_fn(q, req, bio)) + return false; + + trace_block_bio_frontmerge(q, bio); + + if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) + blk_rq_set_mixed_merge(req); + + sector = bio->bi_sector; + + bio->bi_next = req->bio; + req->bio = bio; + + /* + * may not be valid. if the low level driver said + * it didn't need a bounce buffer then it better + * not touch req->buffer either... + */ + req->buffer = bio_data(bio); + req->__sector = bio->bi_sector; + req->__data_len += bio->bi_size; + req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); + + drive_stat_acct(req, 0); + return true; +} + +/* + * Attempts to merge with the plugged list in the current process. Returns + * true if merge was succesful, otherwise false. + */ +static bool attempt_plug_merge(struct task_struct *tsk, struct request_queue *q, + struct bio *bio) +{ + struct blk_plug *plug; + struct request *rq; + bool ret = false; + + plug = tsk->plug; + if (!plug) + goto out; + + list_for_each_entry_reverse(rq, &plug->list, queuelist) { + int el_ret; + + if (rq->q != q) + continue; + + el_ret = elv_try_merge(rq, bio); + if (el_ret == ELEVATOR_BACK_MERGE) { + ret = bio_attempt_back_merge(q, rq, bio); + if (ret) + break; + } else if (el_ret == ELEVATOR_FRONT_MERGE) { + ret = bio_attempt_front_merge(q, rq, bio); + if (ret) + break; + } + } +out: + return ret; +} + void init_request_from_bio(struct request *req, struct bio *bio) { req->cpu = bio->bi_comp_cpu; @@ -1230,26 +1346,12 @@ void init_request_from_bio(struct request *req, struct bio *bio) blk_rq_bio_prep(req->q, req, bio); } -/* - * Only disabling plugging for non-rotational devices if it does tagging - * as well, otherwise we do need the proper merging - */ -static inline bool queue_should_plug(struct request_queue *q) -{ - return !(blk_queue_nonrot(q) && blk_queue_tagged(q)); -} - static int __make_request(struct request_queue *q, struct bio *bio) { - struct request *req; - int el_ret; - unsigned int bytes = bio->bi_size; - const unsigned short prio = bio_prio(bio); const bool sync = !!(bio->bi_rw & REQ_SYNC); - const bool unplug = !!(bio->bi_rw & REQ_UNPLUG); - const unsigned long ff = bio->bi_rw & REQ_FAILFAST_MASK; - int where = ELEVATOR_INSERT_SORT; - int rw_flags; + struct blk_plug *plug; + int el_ret, rw_flags, where = ELEVATOR_INSERT_SORT; + struct request *req; /* * low level driver can indicate that it wants pages above a @@ -1258,78 +1360,36 @@ static int __make_request(struct request_queue *q, struct bio *bio) */ blk_queue_bounce(q, &bio); - spin_lock_irq(q->queue_lock); - if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) { + spin_lock_irq(q->queue_lock); where = ELEVATOR_INSERT_FLUSH; goto get_rq; } - if (elv_queue_empty(q)) - goto get_rq; - - el_ret = elv_merge(q, &req, bio); - switch (el_ret) { - case ELEVATOR_BACK_MERGE: - BUG_ON(!rq_mergeable(req)); - - if (!ll_back_merge_fn(q, req, bio)) - break; - - trace_block_bio_backmerge(q, bio); - - if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) - blk_rq_set_mixed_merge(req); - - req->biotail->bi_next = bio; - req->biotail = bio; - req->__data_len += bytes; - req->ioprio = ioprio_best(req->ioprio, prio); - if (!blk_rq_cpu_valid(req)) - req->cpu = bio->bi_comp_cpu; - drive_stat_acct(req, 0); - elv_bio_merged(q, req, bio); - if (!attempt_back_merge(q, req)) - elv_merged_request(q, req, el_ret); + /* + * Check if we can merge with the plugged list before grabbing + * any locks. + */ + if (attempt_plug_merge(current, q, bio)) goto out; - case ELEVATOR_FRONT_MERGE: - BUG_ON(!rq_mergeable(req)); - - if (!ll_front_merge_fn(q, req, bio)) - break; - - trace_block_bio_frontmerge(q, bio); + spin_lock_irq(q->queue_lock); - if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) { - blk_rq_set_mixed_merge(req); - req->cmd_flags &= ~REQ_FAILFAST_MASK; - req->cmd_flags |= ff; + el_ret = elv_merge(q, &req, bio); + if (el_ret == ELEVATOR_BACK_MERGE) { + BUG_ON(req->cmd_flags & REQ_ON_PLUG); + if (bio_attempt_back_merge(q, req, bio)) { + if (!attempt_back_merge(q, req)) + elv_merged_request(q, req, el_ret); + goto out_unlock; + } + } else if (el_ret == ELEVATOR_FRONT_MERGE) { + BUG_ON(req->cmd_flags & REQ_ON_PLUG); + if (bio_attempt_front_merge(q, req, bio)) { + if (!attempt_front_merge(q, req)) + elv_merged_request(q, req, el_ret); + goto out_unlock; } - - bio->bi_next = req->bio; - req->bio = bio; - - /* - * may not be valid. if the low level driver said - * it didn't need a bounce buffer then it better - * not touch req->buffer either... - */ - req->buffer = bio_data(bio); - req->__sector = bio->bi_sector; - req->__data_len += bytes; - req->ioprio = ioprio_best(req->ioprio, prio); - if (!blk_rq_cpu_valid(req)) - req->cpu = bio->bi_comp_cpu; - drive_stat_acct(req, 0); - elv_bio_merged(q, req, bio); - if (!attempt_front_merge(q, req)) - elv_merged_request(q, req, el_ret); - goto out; - - /* ELV_NO_MERGE: elevator says don't/can't merge. */ - default: - ; } get_rq: @@ -1356,20 +1416,35 @@ get_rq: */ init_request_from_bio(req, bio); - spin_lock_irq(q->queue_lock); if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) || - bio_flagged(bio, BIO_CPU_AFFINE)) - req->cpu = blk_cpu_to_group(smp_processor_id()); - if (queue_should_plug(q) && elv_queue_empty(q)) - blk_plug_device(q); - - /* insert the request into the elevator */ - drive_stat_acct(req, 1); - __elv_add_request(q, req, where, 0); + bio_flagged(bio, BIO_CPU_AFFINE)) { + req->cpu = blk_cpu_to_group(get_cpu()); + put_cpu(); + } + + plug = current->plug; + if (plug && !sync) { + if (!plug->should_sort && !list_empty(&plug->list)) { + struct request *__rq; + + __rq = list_entry_rq(plug->list.prev); + if (__rq->q != q) + plug->should_sort = 1; + } + /* + * Debug flag, kill later + */ + req->cmd_flags |= REQ_ON_PLUG; + list_add_tail(&req->queuelist, &plug->list); + drive_stat_acct(req, 1); + } else { + spin_lock_irq(q->queue_lock); + add_acct_request(q, req, where); + __blk_run_queue(q); +out_unlock: + spin_unlock_irq(q->queue_lock); + } out: - if (unplug || !queue_should_plug(q)) - __generic_unplug_device(q); - spin_unlock_irq(q->queue_lock); return 0; } @@ -1772,9 +1847,7 @@ int blk_insert_cloned_request(struct request_queue *q, struct request *rq) */ BUG_ON(blk_queued_rq(rq)); - drive_stat_acct(rq, 1); - __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0); - + add_acct_request(q, rq, ELEVATOR_INSERT_BACK); spin_unlock_irqrestore(q->queue_lock, flags); return 0; @@ -2659,6 +2732,106 @@ int kblockd_schedule_delayed_work(struct request_queue *q, } EXPORT_SYMBOL(kblockd_schedule_delayed_work); +#define PLUG_MAGIC 0x91827364 + +void blk_start_plug(struct blk_plug *plug) +{ + struct task_struct *tsk = current; + + plug->magic = PLUG_MAGIC; + INIT_LIST_HEAD(&plug->list); + plug->should_sort = 0; + + /* + * If this is a nested plug, don't actually assign it. It will be + * flushed on its own. + */ + if (!tsk->plug) { + /* + * Store ordering should not be needed here, since a potential + * preempt will imply a full memory barrier + */ + tsk->plug = plug; + } +} +EXPORT_SYMBOL(blk_start_plug); + +static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b) +{ + struct request *rqa = container_of(a, struct request, queuelist); + struct request *rqb = container_of(b, struct request, queuelist); + + return !(rqa->q == rqb->q); +} + +static void flush_plug_list(struct blk_plug *plug) +{ + struct request_queue *q; + unsigned long flags; + struct request *rq; + + BUG_ON(plug->magic != PLUG_MAGIC); + + if (list_empty(&plug->list)) + return; + + if (plug->should_sort) + list_sort(NULL, &plug->list, plug_rq_cmp); + + q = NULL; + local_irq_save(flags); + while (!list_empty(&plug->list)) { + rq = list_entry_rq(plug->list.next); + list_del_init(&rq->queuelist); + BUG_ON(!(rq->cmd_flags & REQ_ON_PLUG)); + BUG_ON(!rq->q); + if (rq->q != q) { + if (q) { + __blk_run_queue(q); + spin_unlock(q->queue_lock); + } + q = rq->q; + spin_lock(q->queue_lock); + } + rq->cmd_flags &= ~REQ_ON_PLUG; + + /* + * rq is already accounted, so use raw insert + */ + __elv_add_request(q, rq, ELEVATOR_INSERT_SORT, 0); + } + + if (q) { + __blk_run_queue(q); + spin_unlock(q->queue_lock); + } + + BUG_ON(!list_empty(&plug->list)); + local_irq_restore(flags); +} + +static void __blk_finish_plug(struct task_struct *tsk, struct blk_plug *plug) +{ + flush_plug_list(plug); + + if (plug == tsk->plug) + tsk->plug = NULL; +} + +void blk_finish_plug(struct blk_plug *plug) +{ + if (plug) + __blk_finish_plug(current, plug); +} +EXPORT_SYMBOL(blk_finish_plug); + +void __blk_flush_plug(struct task_struct *tsk, struct blk_plug *plug) +{ + __blk_finish_plug(tsk, plug); + tsk->plug = plug; +} +EXPORT_SYMBOL(__blk_flush_plug); + int __init blk_dev_init(void) { BUILD_BUG_ON(__REQ_NR_BITS > 8 * diff --git a/block/blk-flush.c b/block/blk-flush.c index a867e3f..1e2aa8a 100644 --- a/block/blk-flush.c +++ b/block/blk-flush.c @@ -264,10 +264,9 @@ static bool blk_kick_flush(struct request_queue *q) static void flush_data_end_io(struct request *rq, int error) { struct request_queue *q = rq->q; - bool was_empty = elv_queue_empty(q); /* after populating an empty queue, kick it to avoid stall */ - if (blk_flush_complete_seq(rq, REQ_FSEQ_DATA, error) && was_empty) + if (blk_flush_complete_seq(rq, REQ_FSEQ_DATA, error)) __blk_run_queue(q); } diff --git a/block/elevator.c b/block/elevator.c index f98e92e..2571392 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -113,7 +113,7 @@ int elv_rq_merge_ok(struct request *rq, struct bio *bio) } EXPORT_SYMBOL(elv_rq_merge_ok); -static inline int elv_try_merge(struct request *__rq, struct bio *bio) +int elv_try_merge(struct request *__rq, struct bio *bio) { int ret = ELEVATOR_NO_MERGE; @@ -421,6 +421,8 @@ void elv_dispatch_sort(struct request_queue *q, struct request *rq) struct list_head *entry; int stop_flags; + BUG_ON(rq->cmd_flags & REQ_ON_PLUG); + if (q->last_merge == rq) q->last_merge = NULL; @@ -696,6 +698,8 @@ void elv_insert(struct request_queue *q, struct request *rq, int where) void __elv_add_request(struct request_queue *q, struct request *rq, int where, int plug) { + BUG_ON(rq->cmd_flags & REQ_ON_PLUG); + if (rq->cmd_flags & REQ_SOFTBARRIER) { /* barriers are scheduling boundary, update end_sector */ if (rq->cmd_type == REQ_TYPE_FS || -- cgit v1.1 From 7eaceaccab5f40bbfda044629a6298616aeaed50 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 10 Mar 2011 08:52:07 +0100 Subject: block: remove per-queue plugging Code has been converted over to the new explicit on-stack plugging, and delay users have been converted to use the new API for that. So lets kill off the old plugging along with aops->sync_page(). Signed-off-by: Jens Axboe --- block/blk-core.c | 173 ++++++----------------------------------------- block/blk-exec.c | 4 +- block/blk-flush.c | 3 +- block/blk-settings.c | 8 --- block/blk-throttle.c | 1 - block/blk.h | 2 - block/cfq-iosched.c | 8 --- block/deadline-iosched.c | 9 --- block/elevator.c | 43 +----------- block/noop-iosched.c | 8 --- 10 files changed, 26 insertions(+), 233 deletions(-) (limited to 'block') diff --git a/block/blk-core.c b/block/blk-core.c index 6efb55c..82a4589 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -198,6 +198,19 @@ void blk_dump_rq_flags(struct request *rq, char *msg) } EXPORT_SYMBOL(blk_dump_rq_flags); +/* + * Make sure that plugs that were pending when this function was entered, + * are now complete and requests pushed to the queue. +*/ +static inline void queue_sync_plugs(struct request_queue *q) +{ + /* + * If the current process is plugged and has barriers submitted, + * we will livelock if we don't unplug first. + */ + blk_flush_plug(current); +} + static void blk_delay_work(struct work_struct *work) { struct request_queue *q; @@ -224,137 +237,6 @@ void blk_delay_queue(struct request_queue *q, unsigned long msecs) } EXPORT_SYMBOL(blk_delay_queue); -/* - * "plug" the device if there are no outstanding requests: this will - * force the transfer to start only after we have put all the requests - * on the list. - * - * This is called with interrupts off and no requests on the queue and - * with the queue lock held. - */ -void blk_plug_device(struct request_queue *q) -{ - WARN_ON(!irqs_disabled()); - - /* - * don't plug a stopped queue, it must be paired with blk_start_queue() - * which will restart the queueing - */ - if (blk_queue_stopped(q)) - return; - - if (!queue_flag_test_and_set(QUEUE_FLAG_PLUGGED, q)) { - mod_timer(&q->unplug_timer, jiffies + q->unplug_delay); - trace_block_plug(q); - } -} -EXPORT_SYMBOL(blk_plug_device); - -/** - * blk_plug_device_unlocked - plug a device without queue lock held - * @q: The &struct request_queue to plug - * - * Description: - * Like @blk_plug_device(), but grabs the queue lock and disables - * interrupts. - **/ -void blk_plug_device_unlocked(struct request_queue *q) -{ - unsigned long flags; - - spin_lock_irqsave(q->queue_lock, flags); - blk_plug_device(q); - spin_unlock_irqrestore(q->queue_lock, flags); -} -EXPORT_SYMBOL(blk_plug_device_unlocked); - -/* - * remove the queue from the plugged list, if present. called with - * queue lock held and interrupts disabled. - */ -int blk_remove_plug(struct request_queue *q) -{ - WARN_ON(!irqs_disabled()); - - if (!queue_flag_test_and_clear(QUEUE_FLAG_PLUGGED, q)) - return 0; - - del_timer(&q->unplug_timer); - return 1; -} -EXPORT_SYMBOL(blk_remove_plug); - -/* - * remove the plug and let it rip.. - */ -void __generic_unplug_device(struct request_queue *q) -{ - if (unlikely(blk_queue_stopped(q))) - return; - if (!blk_remove_plug(q) && !blk_queue_nonrot(q)) - return; - - q->request_fn(q); -} - -/** - * generic_unplug_device - fire a request queue - * @q: The &struct request_queue in question - * - * Description: - * Linux uses plugging to build bigger requests queues before letting - * the device have at them. If a queue is plugged, the I/O scheduler - * is still adding and merging requests on the queue. Once the queue - * gets unplugged, the request_fn defined for the queue is invoked and - * transfers started. - **/ -void generic_unplug_device(struct request_queue *q) -{ - if (blk_queue_plugged(q)) { - spin_lock_irq(q->queue_lock); - __generic_unplug_device(q); - spin_unlock_irq(q->queue_lock); - } -} -EXPORT_SYMBOL(generic_unplug_device); - -static void blk_backing_dev_unplug(struct backing_dev_info *bdi, - struct page *page) -{ - struct request_queue *q = bdi->unplug_io_data; - - blk_unplug(q); -} - -void blk_unplug_work(struct work_struct *work) -{ - struct request_queue *q = - container_of(work, struct request_queue, unplug_work); - - trace_block_unplug_io(q); - q->unplug_fn(q); -} - -void blk_unplug_timeout(unsigned long data) -{ - struct request_queue *q = (struct request_queue *)data; - - trace_block_unplug_timer(q); - kblockd_schedule_work(q, &q->unplug_work); -} - -void blk_unplug(struct request_queue *q) -{ - /* - * devices don't necessarily have an ->unplug_fn defined - */ - if (q->unplug_fn) { - trace_block_unplug_io(q); - q->unplug_fn(q); - } -} -EXPORT_SYMBOL(blk_unplug); - /** * blk_start_queue - restart a previously stopped queue * @q: The &struct request_queue in question @@ -389,7 +271,6 @@ EXPORT_SYMBOL(blk_start_queue); **/ void blk_stop_queue(struct request_queue *q) { - blk_remove_plug(q); cancel_delayed_work(&q->delay_work); queue_flag_set(QUEUE_FLAG_STOPPED, q); } @@ -411,11 +292,10 @@ EXPORT_SYMBOL(blk_stop_queue); */ void blk_sync_queue(struct request_queue *q) { - del_timer_sync(&q->unplug_timer); del_timer_sync(&q->timeout); - cancel_work_sync(&q->unplug_work); throtl_shutdown_timer_wq(q); cancel_delayed_work_sync(&q->delay_work); + queue_sync_plugs(q); } EXPORT_SYMBOL(blk_sync_queue); @@ -430,14 +310,9 @@ EXPORT_SYMBOL(blk_sync_queue); */ void __blk_run_queue(struct request_queue *q) { - blk_remove_plug(q); - if (unlikely(blk_queue_stopped(q))) return; - if (elv_queue_empty(q)) - return; - /* * Only recurse once to avoid overrunning the stack, let the unplug * handling reinvoke the handler shortly if we already got there. @@ -445,10 +320,8 @@ void __blk_run_queue(struct request_queue *q) if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) { q->request_fn(q); queue_flag_clear(QUEUE_FLAG_REENTER, q); - } else { - queue_flag_set(QUEUE_FLAG_PLUGGED, q); - kblockd_schedule_work(q, &q->unplug_work); - } + } else + queue_delayed_work(kblockd_workqueue, &q->delay_work, 0); } EXPORT_SYMBOL(__blk_run_queue); @@ -535,8 +408,6 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) if (!q) return NULL; - q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug; - q->backing_dev_info.unplug_io_data = q; q->backing_dev_info.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE; q->backing_dev_info.state = 0; @@ -556,13 +427,11 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) setup_timer(&q->backing_dev_info.laptop_mode_wb_timer, laptop_mode_timer_fn, (unsigned long) q); - init_timer(&q->unplug_timer); setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q); INIT_LIST_HEAD(&q->timeout_list); INIT_LIST_HEAD(&q->flush_queue[0]); INIT_LIST_HEAD(&q->flush_queue[1]); INIT_LIST_HEAD(&q->flush_data_in_flight); - INIT_WORK(&q->unplug_work, blk_unplug_work); INIT_DELAYED_WORK(&q->delay_work, blk_delay_work); kobject_init(&q->kobj, &blk_queue_ktype); @@ -652,7 +521,6 @@ blk_init_allocated_queue_node(struct request_queue *q, request_fn_proc *rfn, q->request_fn = rfn; q->prep_rq_fn = NULL; q->unprep_rq_fn = NULL; - q->unplug_fn = generic_unplug_device; q->queue_flags = QUEUE_FLAG_DEFAULT; q->queue_lock = lock; @@ -910,8 +778,8 @@ out: } /* - * No available requests for this queue, unplug the device and wait for some - * requests to become available. + * No available requests for this queue, wait for some requests to become + * available. * * Called with q->queue_lock held, and returns with it unlocked. */ @@ -932,7 +800,6 @@ static struct request *get_request_wait(struct request_queue *q, int rw_flags, trace_block_sleeprq(q, bio, rw_flags & 1); - __generic_unplug_device(q); spin_unlock_irq(q->queue_lock); io_schedule(); @@ -1058,7 +925,7 @@ static void add_acct_request(struct request_queue *q, struct request *rq, int where) { drive_stat_acct(rq, 1); - __elv_add_request(q, rq, where, 0); + __elv_add_request(q, rq, where); } /** @@ -2798,7 +2665,7 @@ static void flush_plug_list(struct blk_plug *plug) /* * rq is already accounted, so use raw insert */ - __elv_add_request(q, rq, ELEVATOR_INSERT_SORT, 0); + __elv_add_request(q, rq, ELEVATOR_INSERT_SORT); } if (q) { diff --git a/block/blk-exec.c b/block/blk-exec.c index cf1456a..81e3181 100644 --- a/block/blk-exec.c +++ b/block/blk-exec.c @@ -54,8 +54,8 @@ void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk, rq->end_io = done; WARN_ON(irqs_disabled()); spin_lock_irq(q->queue_lock); - __elv_add_request(q, rq, where, 1); - __generic_unplug_device(q); + __elv_add_request(q, rq, where); + __blk_run_queue(q); /* the queue is stopped so it won't be plugged+unplugged */ if (rq->cmd_type == REQ_TYPE_PM_RESUME) q->request_fn(q); diff --git a/block/blk-flush.c b/block/blk-flush.c index 1e2aa8a..671fa9d 100644 --- a/block/blk-flush.c +++ b/block/blk-flush.c @@ -194,7 +194,6 @@ static void flush_end_io(struct request *flush_rq, int error) { struct request_queue *q = flush_rq->q; struct list_head *running = &q->flush_queue[q->flush_running_idx]; - bool was_empty = elv_queue_empty(q); bool queued = false; struct request *rq, *n; @@ -213,7 +212,7 @@ static void flush_end_io(struct request *flush_rq, int error) } /* after populating an empty queue, kick it to avoid stall */ - if (queued && was_empty) + if (queued) __blk_run_queue(q); } diff --git a/block/blk-settings.c b/block/blk-settings.c index 36c8c1f..c8d6892 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -164,14 +164,6 @@ void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn) blk_queue_congestion_threshold(q); q->nr_batching = BLK_BATCH_REQ; - q->unplug_thresh = 4; /* hmm */ - q->unplug_delay = msecs_to_jiffies(3); /* 3 milliseconds */ - if (q->unplug_delay == 0) - q->unplug_delay = 1; - - q->unplug_timer.function = blk_unplug_timeout; - q->unplug_timer.data = (unsigned long)q; - blk_set_default_limits(&q->limits); blk_queue_max_hw_sectors(q, BLK_SAFE_MAX_SECTORS); diff --git a/block/blk-throttle.c b/block/blk-throttle.c index a89043a..b8dcdc2 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -800,7 +800,6 @@ out: if (nr_disp) { while((bio = bio_list_pop(&bio_list_on_stack))) generic_make_request(bio); - blk_unplug(q); } return nr_disp; } diff --git a/block/blk.h b/block/blk.h index 284b500..49d21af 100644 --- a/block/blk.h +++ b/block/blk.h @@ -18,8 +18,6 @@ int blk_rq_append_bio(struct request_queue *q, struct request *rq, void blk_dequeue_request(struct request *rq); void __blk_queue_free_tags(struct request_queue *q); -void blk_unplug_work(struct work_struct *work); -void blk_unplug_timeout(unsigned long data); void blk_rq_timed_out_timer(unsigned long data); void blk_delete_timer(struct request *); void blk_add_timer(struct request *); diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 3202c7e..ef63153 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -499,13 +499,6 @@ static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) } } -static int cfq_queue_empty(struct request_queue *q) -{ - struct cfq_data *cfqd = q->elevator->elevator_data; - - return !cfqd->rq_queued; -} - /* * Scale schedule slice based on io priority. Use the sync time slice only * if a queue is marked sync and has sync io queued. A sync queue with async @@ -4061,7 +4054,6 @@ static struct elevator_type iosched_cfq = { .elevator_add_req_fn = cfq_insert_request, .elevator_activate_req_fn = cfq_activate_request, .elevator_deactivate_req_fn = cfq_deactivate_request, - .elevator_queue_empty_fn = cfq_queue_empty, .elevator_completed_req_fn = cfq_completed_request, .elevator_former_req_fn = elv_rb_former_request, .elevator_latter_req_fn = elv_rb_latter_request, diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c index b547cbc..5139c0e 100644 --- a/block/deadline-iosched.c +++ b/block/deadline-iosched.c @@ -326,14 +326,6 @@ dispatch_request: return 1; } -static int deadline_queue_empty(struct request_queue *q) -{ - struct deadline_data *dd = q->elevator->elevator_data; - - return list_empty(&dd->fifo_list[WRITE]) - && list_empty(&dd->fifo_list[READ]); -} - static void deadline_exit_queue(struct elevator_queue *e) { struct deadline_data *dd = e->elevator_data; @@ -445,7 +437,6 @@ static struct elevator_type iosched_deadline = { .elevator_merge_req_fn = deadline_merged_requests, .elevator_dispatch_fn = deadline_dispatch_requests, .elevator_add_req_fn = deadline_add_request, - .elevator_queue_empty_fn = deadline_queue_empty, .elevator_former_req_fn = elv_rb_former_request, .elevator_latter_req_fn = elv_rb_latter_request, .elevator_init_fn = deadline_init_queue, diff --git a/block/elevator.c b/block/elevator.c index 2571392..3ea2082 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -619,21 +619,12 @@ void elv_quiesce_end(struct request_queue *q) void elv_insert(struct request_queue *q, struct request *rq, int where) { - int unplug_it = 1; - trace_block_rq_insert(q, rq); rq->q = q; switch (where) { case ELEVATOR_INSERT_REQUEUE: - /* - * Most requeues happen because of a busy condition, - * don't force unplug of the queue for that case. - * Clear unplug_it and fall through. - */ - unplug_it = 0; - case ELEVATOR_INSERT_FRONT: rq->cmd_flags |= REQ_SOFTBARRIER; list_add(&rq->queuelist, &q->queue_head); @@ -679,24 +670,14 @@ void elv_insert(struct request_queue *q, struct request *rq, int where) rq->cmd_flags |= REQ_SOFTBARRIER; blk_insert_flush(rq); break; - default: printk(KERN_ERR "%s: bad insertion point %d\n", __func__, where); BUG(); } - - if (unplug_it && blk_queue_plugged(q)) { - int nrq = q->rq.count[BLK_RW_SYNC] + q->rq.count[BLK_RW_ASYNC] - - queue_in_flight(q); - - if (nrq >= q->unplug_thresh) - __generic_unplug_device(q); - } } -void __elv_add_request(struct request_queue *q, struct request *rq, int where, - int plug) +void __elv_add_request(struct request_queue *q, struct request *rq, int where) { BUG_ON(rq->cmd_flags & REQ_ON_PLUG); @@ -711,38 +692,20 @@ void __elv_add_request(struct request_queue *q, struct request *rq, int where, where == ELEVATOR_INSERT_SORT) where = ELEVATOR_INSERT_BACK; - if (plug) - blk_plug_device(q); - elv_insert(q, rq, where); } EXPORT_SYMBOL(__elv_add_request); -void elv_add_request(struct request_queue *q, struct request *rq, int where, - int plug) +void elv_add_request(struct request_queue *q, struct request *rq, int where) { unsigned long flags; spin_lock_irqsave(q->queue_lock, flags); - __elv_add_request(q, rq, where, plug); + __elv_add_request(q, rq, where); spin_unlock_irqrestore(q->queue_lock, flags); } EXPORT_SYMBOL(elv_add_request); -int elv_queue_empty(struct request_queue *q) -{ - struct elevator_queue *e = q->elevator; - - if (!list_empty(&q->queue_head)) - return 0; - - if (e->ops->elevator_queue_empty_fn) - return e->ops->elevator_queue_empty_fn(q); - - return 1; -} -EXPORT_SYMBOL(elv_queue_empty); - struct request *elv_latter_request(struct request_queue *q, struct request *rq) { struct elevator_queue *e = q->elevator; diff --git a/block/noop-iosched.c b/block/noop-iosched.c index 232c4b3..06389e9 100644 --- a/block/noop-iosched.c +++ b/block/noop-iosched.c @@ -39,13 +39,6 @@ static void noop_add_request(struct request_queue *q, struct request *rq) list_add_tail(&rq->queuelist, &nd->queue); } -static int noop_queue_empty(struct request_queue *q) -{ - struct noop_data *nd = q->elevator->elevator_data; - - return list_empty(&nd->queue); -} - static struct request * noop_former_request(struct request_queue *q, struct request *rq) { @@ -90,7 +83,6 @@ static struct elevator_type elevator_noop = { .elevator_merge_req_fn = noop_merged_requests, .elevator_dispatch_fn = noop_dispatch, .elevator_add_req_fn = noop_add_request, - .elevator_queue_empty_fn = noop_queue_empty, .elevator_former_req_fn = noop_former_request, .elevator_latter_req_fn = noop_latter_request, .elevator_init_fn = noop_init_queue, -- cgit v1.1 From 721a9602e6607417c6bc15b18e97a2f35266c690 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 9 Mar 2011 11:56:30 +0100 Subject: block: kill off REQ_UNPLUG With the plugging now being explicitly controlled by the submitter, callers need not pass down unplugging hints to the block layer. If they want to unplug, it's because they manually plugged on their own - in which case, they should just unplug at will. Signed-off-by: Jens Axboe --- block/blk-core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'block') diff --git a/block/blk-core.c b/block/blk-core.c index 82a4589..7e9715a 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1290,7 +1290,7 @@ get_rq: } plug = current->plug; - if (plug && !sync) { + if (plug) { if (!plug->should_sort && !list_empty(&plug->list)) { struct request *__rq; -- cgit v1.1 From 69d60eb96ae8a73cf9b79cf28051caf973006011 Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Wed, 9 Mar 2011 08:27:37 +0100 Subject: blk-throttle: Use blk_plug in throttle dispatch Use plug in throttle dispatch also as we are dispatching a bunch of bios in throttle context and some of them might merge. Signed-off-by: Vivek Goyal Signed-off-by: Jens Axboe --- block/blk-throttle.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'block') diff --git a/block/blk-throttle.c b/block/blk-throttle.c index b8dcdc2..658ee50 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -770,6 +770,7 @@ static int throtl_dispatch(struct request_queue *q) unsigned int nr_disp = 0; struct bio_list bio_list_on_stack; struct bio *bio; + struct blk_plug plug; spin_lock_irq(q->queue_lock); @@ -798,8 +799,10 @@ out: * immediate dispatch */ if (nr_disp) { + blk_start_plug(&plug); while((bio = bio_list_pop(&bio_list_on_stack))) generic_make_request(bio); + blk_finish_plug(&plug); } return nr_disp; } -- cgit v1.1 From eba2ed9c9636d9e7ed203a2498ed230b48341709 Mon Sep 17 00:00:00 2001 From: Tao Ma Date: Fri, 11 Mar 2011 20:13:54 +0100 Subject: block: remove obsolete comments for blkdev_issue_zeroout. barrier is already removed, so remove the obsolete comments in blkdev_issue_zeroout. Cc: Jens Axboe Signed-off-by: Tao Ma Signed-off-by: Jens Axboe --- block/blk-lib.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'block') diff --git a/block/blk-lib.c b/block/blk-lib.c index eec78be..cb56c4e 100644 --- a/block/blk-lib.c +++ b/block/blk-lib.c @@ -140,8 +140,6 @@ static void bio_batch_end_io(struct bio *bio, int err) * * Description: * Generate and issue number of bios with zerofiled pages. - * Send barrier at the beginning and at the end if requested. This guarantie - * correct request ordering. Empty barrier allow us to avoid post queue flush. */ int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector, -- cgit v1.1 From 167400d34070ebbc408dc0f447c4ddb4bf837360 Mon Sep 17 00:00:00 2001 From: Justin TerAvest Date: Sat, 12 Mar 2011 16:54:00 +0100 Subject: blk-cgroup: Add unaccounted time to timeslice_used. There are two kind of times that tasks are not charged for: the first seek and the extra time slice used over the allocated timeslice. Both of these exported as a new unaccounted_time stat. I think it would be good to have this reported in 'time' as well, but that is probably a separate discussion. Signed-off-by: Justin TerAvest Signed-off-by: Jens Axboe --- block/blk-cgroup.c | 16 +++++++++++++++- block/blk-cgroup.h | 12 ++++++++++-- block/cfq-iosched.c | 21 +++++++++++++-------- block/cfq.h | 6 +++--- 4 files changed, 41 insertions(+), 14 deletions(-) (limited to 'block') diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 455768a..77ee3c1 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -371,12 +371,14 @@ void blkiocg_update_io_remove_stats(struct blkio_group *blkg, } EXPORT_SYMBOL_GPL(blkiocg_update_io_remove_stats); -void blkiocg_update_timeslice_used(struct blkio_group *blkg, unsigned long time) +void blkiocg_update_timeslice_used(struct blkio_group *blkg, unsigned long time, + unsigned long unaccounted_time) { unsigned long flags; spin_lock_irqsave(&blkg->stats_lock, flags); blkg->stats.time += time; + blkg->stats.unaccounted_time += unaccounted_time; spin_unlock_irqrestore(&blkg->stats_lock, flags); } EXPORT_SYMBOL_GPL(blkiocg_update_timeslice_used); @@ -603,6 +605,9 @@ static uint64_t blkio_get_stat(struct blkio_group *blkg, if (type == BLKIO_STAT_SECTORS) return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, blkg->stats.sectors, cb, dev); + if (type == BLKIO_STAT_UNACCOUNTED_TIME) + return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, + blkg->stats.unaccounted_time, cb, dev); #ifdef CONFIG_DEBUG_BLK_CGROUP if (type == BLKIO_STAT_AVG_QUEUE_SIZE) { uint64_t sum = blkg->stats.avg_queue_size_sum; @@ -1106,6 +1111,9 @@ static int blkiocg_file_read_map(struct cgroup *cgrp, struct cftype *cft, case BLKIO_PROP_sectors: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_SECTORS, 0); + case BLKIO_PROP_unaccounted_time: + return blkio_read_blkg_stats(blkcg, cft, cb, + BLKIO_STAT_UNACCOUNTED_TIME, 0); case BLKIO_PROP_io_service_bytes: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_SERVICE_BYTES, 1); @@ -1262,6 +1270,12 @@ struct cftype blkio_files[] = { .read_map = blkiocg_file_read_map, }, { + .name = "unaccounted_time", + .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, + BLKIO_PROP_unaccounted_time), + .read_map = blkiocg_file_read_map, + }, + { .name = "io_service_bytes", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, BLKIO_PROP_io_service_bytes), diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h index 57e7234..10919fa 100644 --- a/block/blk-cgroup.h +++ b/block/blk-cgroup.h @@ -49,6 +49,8 @@ enum stat_type { /* All the single valued stats go below this */ BLKIO_STAT_TIME, BLKIO_STAT_SECTORS, + /* Time not charged to this cgroup */ + BLKIO_STAT_UNACCOUNTED_TIME, #ifdef CONFIG_DEBUG_BLK_CGROUP BLKIO_STAT_AVG_QUEUE_SIZE, BLKIO_STAT_IDLE_TIME, @@ -81,6 +83,7 @@ enum blkcg_file_name_prop { BLKIO_PROP_io_serviced, BLKIO_PROP_time, BLKIO_PROP_sectors, + BLKIO_PROP_unaccounted_time, BLKIO_PROP_io_service_time, BLKIO_PROP_io_wait_time, BLKIO_PROP_io_merged, @@ -114,6 +117,8 @@ struct blkio_group_stats { /* total disk time and nr sectors dispatched by this group */ uint64_t time; uint64_t sectors; + /* Time not charged to this cgroup */ + uint64_t unaccounted_time; uint64_t stat_arr[BLKIO_STAT_QUEUED + 1][BLKIO_STAT_TOTAL]; #ifdef CONFIG_DEBUG_BLK_CGROUP /* Sum of number of IOs queued across all samples */ @@ -293,7 +298,8 @@ extern int blkiocg_del_blkio_group(struct blkio_group *blkg); extern struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key); void blkiocg_update_timeslice_used(struct blkio_group *blkg, - unsigned long time); + unsigned long time, + unsigned long unaccounted_time); void blkiocg_update_dispatch_stats(struct blkio_group *blkg, uint64_t bytes, bool direction, bool sync); void blkiocg_update_completion_stats(struct blkio_group *blkg, @@ -319,7 +325,9 @@ blkiocg_del_blkio_group(struct blkio_group *blkg) { return 0; } static inline struct blkio_group * blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key) { return NULL; } static inline void blkiocg_update_timeslice_used(struct blkio_group *blkg, - unsigned long time) {} + unsigned long time, + unsigned long unaccounted_time) +{} static inline void blkiocg_update_dispatch_stats(struct blkio_group *blkg, uint64_t bytes, bool direction, bool sync) {} static inline void blkiocg_update_completion_stats(struct blkio_group *blkg, diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index c826ef8..89e0d1c 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -899,7 +899,8 @@ cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg) cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1); } -static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq) +static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq, + unsigned int *unaccounted_time) { unsigned int slice_used; @@ -918,8 +919,13 @@ static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq) 1); } else { slice_used = jiffies - cfqq->slice_start; - if (slice_used > cfqq->allocated_slice) + if (slice_used > cfqq->allocated_slice) { + *unaccounted_time = slice_used - cfqq->allocated_slice; slice_used = cfqq->allocated_slice; + } + if (time_after(cfqq->slice_start, cfqq->dispatch_start)) + *unaccounted_time += cfqq->slice_start - + cfqq->dispatch_start; } return slice_used; @@ -929,12 +935,12 @@ static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg, struct cfq_queue *cfqq) { struct cfq_rb_root *st = &cfqd->grp_service_tree; - unsigned int used_sl, charge; + unsigned int used_sl, charge, unaccounted_sl = 0; int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg) - cfqg->service_tree_idle.count; BUG_ON(nr_sync < 0); - used_sl = charge = cfq_cfqq_slice_usage(cfqq); + used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl); if (iops_mode(cfqd)) charge = cfqq->slice_dispatch; @@ -960,7 +966,8 @@ static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg, cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%u disp=%u charge=%u iops=%u" " sect=%u", used_sl, cfqq->slice_dispatch, charge, iops_mode(cfqd), cfqq->nr_sectors); - cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl); + cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl, + unaccounted_sl); cfq_blkiocg_set_start_empty_time(&cfqg->blkg); } @@ -3296,9 +3303,7 @@ static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) BUG_ON(!cfq_cfqq_on_rr(cfqq)); cfq_service_tree_add(cfqd, cfqq, 1); - - cfqq->slice_end = 0; - cfq_mark_cfqq_slice_new(cfqq); + __cfq_set_active_queue(cfqd, cfqq); } /* diff --git a/block/cfq.h b/block/cfq.h index 54a6d90..2a15592 100644 --- a/block/cfq.h +++ b/block/cfq.h @@ -16,9 +16,9 @@ static inline void cfq_blkiocg_update_dequeue_stats(struct blkio_group *blkg, } static inline void cfq_blkiocg_update_timeslice_used(struct blkio_group *blkg, - unsigned long time) + unsigned long time, unsigned long unaccounted_time) { - blkiocg_update_timeslice_used(blkg, time); + blkiocg_update_timeslice_used(blkg, time, unaccounted_time); } static inline void cfq_blkiocg_set_start_empty_time(struct blkio_group *blkg) @@ -85,7 +85,7 @@ static inline void cfq_blkiocg_update_dequeue_stats(struct blkio_group *blkg, unsigned long dequeue) {} static inline void cfq_blkiocg_update_timeslice_used(struct blkio_group *blkg, - unsigned long time) {} + unsigned long time, unsigned long unaccounted_time) {} static inline void cfq_blkiocg_set_start_empty_time(struct blkio_group *blkg) {} static inline void cfq_blkiocg_update_io_remove_stats(struct blkio_group *blkg, bool direction, bool sync) {} -- cgit v1.1 From 8184f93eced1e304721c2a55c00d87d5a14f8907 Mon Sep 17 00:00:00 2001 From: Justin TerAvest Date: Thu, 17 Mar 2011 16:12:36 +0100 Subject: cfq-iosched: Don't update group weights when on service tree Version 3 is updated to apply to for-2.6.39/core. For version 2, I took Vivek's advice and made sure we update the group weight from cfq_group_service_tree_add(). If a weight was updated while a group is on the service tree, the calculation for the total weight of the service tree can be adjusted improperly, which either leads to bad service tree weights, or potentially crashes (if total_weight becomes 0). This patch defers updates to the weight until a group is off the service tree. Signed-off-by: Justin TerAvest Acked-by: Vivek Goyal Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 53 +++++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 41 insertions(+), 12 deletions(-) (limited to 'block') diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 89e0d1c..12e380b 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -178,6 +178,8 @@ struct cfq_group { /* group service_tree key */ u64 vdisktime; unsigned int weight; + unsigned int new_weight; + bool needs_update; /* number of cfqq currently on this group */ int nr_cfqq; @@ -853,7 +855,27 @@ __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) } static void -cfq_group_service_tree_add(struct cfq_data *cfqd, struct cfq_group *cfqg) +cfq_update_group_weight(struct cfq_group *cfqg) +{ + BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node)); + if (cfqg->needs_update) { + cfqg->weight = cfqg->new_weight; + cfqg->needs_update = false; + } +} + +static void +cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) +{ + BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node)); + + cfq_update_group_weight(cfqg); + __cfq_group_service_tree_add(st, cfqg); + st->total_weight += cfqg->weight; +} + +static void +cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg) { struct cfq_rb_root *st = &cfqd->grp_service_tree; struct cfq_group *__cfqg; @@ -874,13 +896,19 @@ cfq_group_service_tree_add(struct cfq_data *cfqd, struct cfq_group *cfqg) cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY; } else cfqg->vdisktime = st->min_vdisktime; + cfq_group_service_tree_add(st, cfqg); +} - __cfq_group_service_tree_add(st, cfqg); - st->total_weight += cfqg->weight; +static void +cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg) +{ + st->total_weight -= cfqg->weight; + if (!RB_EMPTY_NODE(&cfqg->rb_node)) + cfq_rb_erase(&cfqg->rb_node, st); } static void -cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg) +cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg) { struct cfq_rb_root *st = &cfqd->grp_service_tree; @@ -892,9 +920,7 @@ cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg) return; cfq_log_cfqg(cfqd, cfqg, "del_from_rr group"); - st->total_weight -= cfqg->weight; - if (!RB_EMPTY_NODE(&cfqg->rb_node)) - cfq_rb_erase(&cfqg->rb_node, st); + cfq_group_service_tree_del(st, cfqg); cfqg->saved_workload_slice = 0; cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1); } @@ -948,9 +974,10 @@ static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg, charge = cfqq->allocated_slice; /* Can't update vdisktime while group is on service tree */ - cfq_rb_erase(&cfqg->rb_node, st); + cfq_group_service_tree_del(st, cfqg); cfqg->vdisktime += cfq_scale_slice(charge, cfqg); - __cfq_group_service_tree_add(st, cfqg); + /* If a new weight was requested, update now, off tree */ + cfq_group_service_tree_add(st, cfqg); /* This group is being expired. Save the context */ if (time_after(cfqd->workload_expires, jiffies)) { @@ -982,7 +1009,9 @@ static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg) void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg, unsigned int weight) { - cfqg_of_blkg(blkg)->weight = weight; + struct cfq_group *cfqg = cfqg_of_blkg(blkg); + cfqg->new_weight = weight; + cfqg->needs_update = true; } static struct cfq_group * @@ -1255,7 +1284,7 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, service_tree->count++; if ((add_front || !new_cfqq) && !group_changed) return; - cfq_group_service_tree_add(cfqd, cfqq->cfqg); + cfq_group_notify_queue_add(cfqd, cfqq->cfqg); } static struct cfq_queue * @@ -1368,7 +1397,7 @@ static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) cfqq->p_root = NULL; } - cfq_group_service_tree_del(cfqd, cfqq->cfqg); + cfq_group_notify_queue_del(cfqd, cfqq->cfqg); BUG_ON(!cfqd->busy_queues); cfqd->busy_queues--; if (cfq_cfqq_sync(cfqq)) -- cgit v1.1 From 5e84ea3a9c662dc2d7a48703a4468fad954a3b7f Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Mon, 21 Mar 2011 10:14:27 +0100 Subject: block: attempt to merge with existing requests on plug flush One of the disadvantages of on-stack plugging is that we potentially lose out on merging since all pending IO isn't always visible to everybody. When we flush the on-stack plugs, right now we don't do any checks to see if potential merge candidates could be utilized. Correct this by adding a new insert variant, ELEVATOR_INSERT_SORT_MERGE. It works just ELEVATOR_INSERT_SORT, but first checks whether we can merge with an existing request before doing the insertion (if we fail merging). This fixes a regression with multiple processes issuing IO that can be merged. Thanks to Shaohua Li for testing and fixing an accounting bug. Signed-off-by: Jens Axboe --- block/blk-core.c | 2 +- block/blk-merge.c | 6 ++++++ block/blk.h | 2 ++ block/elevator.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++--- 4 files changed, 58 insertions(+), 4 deletions(-) (limited to 'block') diff --git a/block/blk-core.c b/block/blk-core.c index e1fcf7a..5256932 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -2685,7 +2685,7 @@ static void flush_plug_list(struct blk_plug *plug) /* * rq is already accounted, so use raw insert */ - __elv_add_request(q, rq, ELEVATOR_INSERT_SORT); + __elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE); } if (q) { diff --git a/block/blk-merge.c b/block/blk-merge.c index ea85e20..cfcc37c 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -465,3 +465,9 @@ int attempt_front_merge(struct request_queue *q, struct request *rq) return 0; } + +int blk_attempt_req_merge(struct request_queue *q, struct request *rq, + struct request *next) +{ + return attempt_merge(q, rq, next); +} diff --git a/block/blk.h b/block/blk.h index 49d21af..c8db371 100644 --- a/block/blk.h +++ b/block/blk.h @@ -103,6 +103,8 @@ int ll_front_merge_fn(struct request_queue *q, struct request *req, struct bio *bio); int attempt_back_merge(struct request_queue *q, struct request *rq); int attempt_front_merge(struct request_queue *q, struct request *rq); +int blk_attempt_req_merge(struct request_queue *q, struct request *rq, + struct request *next); void blk_recalc_rq_segments(struct request *rq); void blk_rq_set_mixed_merge(struct request *rq); diff --git a/block/elevator.c b/block/elevator.c index 542ce82..c387d31 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -521,6 +521,40 @@ int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) return ELEVATOR_NO_MERGE; } +/* + * Attempt to do an insertion back merge. Only check for the case where + * we can append 'rq' to an existing request, so we can throw 'rq' away + * afterwards. + * + * Returns true if we merged, false otherwise + */ +static bool elv_attempt_insert_merge(struct request_queue *q, + struct request *rq) +{ + struct request *__rq; + + if (blk_queue_nomerges(q)) + return false; + + /* + * First try one-hit cache. + */ + if (q->last_merge && blk_attempt_req_merge(q, q->last_merge, rq)) + return true; + + if (blk_queue_noxmerges(q)) + return false; + + /* + * See if our hash lookup can find a potential backmerge. + */ + __rq = elv_rqhash_find(q, blk_rq_pos(rq)); + if (__rq && blk_attempt_req_merge(q, __rq, rq)) + return true; + + return false; +} + void elv_merged_request(struct request_queue *q, struct request *rq, int type) { struct elevator_queue *e = q->elevator; @@ -538,14 +572,18 @@ void elv_merge_requests(struct request_queue *q, struct request *rq, struct request *next) { struct elevator_queue *e = q->elevator; + const int next_sorted = next->cmd_flags & REQ_SORTED; - if (e->ops->elevator_merge_req_fn) + if (next_sorted && e->ops->elevator_merge_req_fn) e->ops->elevator_merge_req_fn(q, rq, next); elv_rqhash_reposition(q, rq); - elv_rqhash_del(q, next); - q->nr_sorted--; + if (next_sorted) { + elv_rqhash_del(q, next); + q->nr_sorted--; + } + q->last_merge = rq; } @@ -647,6 +685,14 @@ void elv_insert(struct request_queue *q, struct request *rq, int where) __blk_run_queue(q, false); break; + case ELEVATOR_INSERT_SORT_MERGE: + /* + * If we succeed in merging this request with one in the + * queue already, we are done - rq has now been freed, + * so no need to do anything further. + */ + if (elv_attempt_insert_merge(q, rq)) + break; case ELEVATOR_INSERT_SORT: BUG_ON(rq->cmd_type != REQ_TYPE_FS && !(rq->cmd_flags & REQ_DISCARD)); -- cgit v1.1 From eda5e0c91fed2d2a38a341b0957263406d330274 Mon Sep 17 00:00:00 2001 From: Justin TerAvest Date: Tue, 22 Mar 2011 21:26:49 +0100 Subject: cfq-iosched: Don't set active queue in preempt Commit "Add unaccounted time to timeslice_used" changed the behavior of cfq_preempt_queue to set cfqq active. Vivek pointed out that other preemption rules might get involved, so we shouldn't manually set which queue is active. This cleans up the code to just clear the queue stats at preemption time. Signed-off-by: Justin TerAvest Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 39 +++++++++++++++++++++++---------------- 1 file changed, 23 insertions(+), 16 deletions(-) (limited to 'block') diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 12e380b..69208d7 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1620,27 +1620,33 @@ static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq) cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg); } +static void cfq_clear_queue_stats(struct cfq_data *cfqd, + struct cfq_queue *cfqq) +{ + cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg); + cfqq->slice_start = 0; + cfqq->dispatch_start = jiffies; + cfqq->allocated_slice = 0; + cfqq->slice_end = 0; + cfqq->slice_dispatch = 0; + cfqq->nr_sectors = 0; + + cfq_clear_cfqq_wait_request(cfqq); + cfq_clear_cfqq_must_dispatch(cfqq); + cfq_clear_cfqq_must_alloc_slice(cfqq); + cfq_clear_cfqq_fifo_expire(cfqq); + cfq_mark_cfqq_slice_new(cfqq); + + cfq_del_timer(cfqd, cfqq); +} + static void __cfq_set_active_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) { if (cfqq) { cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d", cfqd->serving_prio, cfqd->serving_type); - cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg); - cfqq->slice_start = 0; - cfqq->dispatch_start = jiffies; - cfqq->allocated_slice = 0; - cfqq->slice_end = 0; - cfqq->slice_dispatch = 0; - cfqq->nr_sectors = 0; - - cfq_clear_cfqq_wait_request(cfqq); - cfq_clear_cfqq_must_dispatch(cfqq); - cfq_clear_cfqq_must_alloc_slice(cfqq); - cfq_clear_cfqq_fifo_expire(cfqq); - cfq_mark_cfqq_slice_new(cfqq); - - cfq_del_timer(cfqd, cfqq); + cfq_clear_queue_stats(cfqd, cfqq); } cfqd->active_queue = cfqq; @@ -3332,7 +3338,8 @@ static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) BUG_ON(!cfq_cfqq_on_rr(cfqq)); cfq_service_tree_add(cfqd, cfqq, 1); - __cfq_set_active_queue(cfqd, cfqq); + + cfq_clear_queue_stats(cfqd, cfqq); } /* -- cgit v1.1 From 9026e521c0da0731eb31f9f9022dd00cc3cd8885 Mon Sep 17 00:00:00 2001 From: Justin TerAvest Date: Tue, 22 Mar 2011 21:26:54 +0100 Subject: blk-cgroup: Only give unaccounted_time under debug This change moves unaccounted_time to only be reported when CONFIG_DEBUG_BLK_CGROUP is true. Signed-off-by: Justin TerAvest Signed-off-by: Jens Axboe --- block/blk-cgroup.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) (limited to 'block') diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 77ee3c1..2bef570 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -605,10 +605,10 @@ static uint64_t blkio_get_stat(struct blkio_group *blkg, if (type == BLKIO_STAT_SECTORS) return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, blkg->stats.sectors, cb, dev); +#ifdef CONFIG_DEBUG_BLK_CGROUP if (type == BLKIO_STAT_UNACCOUNTED_TIME) return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, blkg->stats.unaccounted_time, cb, dev); -#ifdef CONFIG_DEBUG_BLK_CGROUP if (type == BLKIO_STAT_AVG_QUEUE_SIZE) { uint64_t sum = blkg->stats.avg_queue_size_sum; uint64_t samples = blkg->stats.avg_queue_size_samples; @@ -1111,9 +1111,6 @@ static int blkiocg_file_read_map(struct cgroup *cgrp, struct cftype *cft, case BLKIO_PROP_sectors: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_SECTORS, 0); - case BLKIO_PROP_unaccounted_time: - return blkio_read_blkg_stats(blkcg, cft, cb, - BLKIO_STAT_UNACCOUNTED_TIME, 0); case BLKIO_PROP_io_service_bytes: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_SERVICE_BYTES, 1); @@ -1133,6 +1130,9 @@ static int blkiocg_file_read_map(struct cgroup *cgrp, struct cftype *cft, return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_QUEUED, 1); #ifdef CONFIG_DEBUG_BLK_CGROUP + case BLKIO_PROP_unaccounted_time: + return blkio_read_blkg_stats(blkcg, cft, cb, + BLKIO_STAT_UNACCOUNTED_TIME, 0); case BLKIO_PROP_dequeue: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_DEQUEUE, 0); @@ -1270,12 +1270,6 @@ struct cftype blkio_files[] = { .read_map = blkiocg_file_read_map, }, { - .name = "unaccounted_time", - .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, - BLKIO_PROP_unaccounted_time), - .read_map = blkiocg_file_read_map, - }, - { .name = "io_service_bytes", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, BLKIO_PROP_io_service_bytes), @@ -1396,6 +1390,12 @@ struct cftype blkio_files[] = { BLKIO_PROP_dequeue), .read_map = blkiocg_file_read_map, }, + { + .name = "unaccounted_time", + .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, + BLKIO_PROP_unaccounted_time), + .read_map = blkiocg_file_read_map, + }, #endif }; -- cgit v1.1 From 04521db04e9a11e74b0252d222051cb194487f4d Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Tue, 22 Mar 2011 21:54:29 +0100 Subject: blk-throttle: Reset group slice when limits are changed Lina reported that if throttle limits are initially very high and then dropped, then no new bio might be dispatched for a long time. And the reason being that after dropping the limits we don't reset the existing slice and do the rate calculation with new low rate and account the bios dispatched at high rate. To fix it, reset the slice upon rate change. https://lkml.org/lkml/2011/3/10/298 Another problem with very high limit is that we never queued the bio on throtl service tree. That means we kept on extending the group slice but never trimmed it. Fix that also by regulary trimming the slice even if bio is not being queued up. Reported-by: Lina Lu Signed-off-by: Vivek Goyal Signed-off-by: Jens Axboe --- block/blk-throttle.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) (limited to 'block') diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 37abbfc..5352bda 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -756,6 +756,15 @@ static void throtl_process_limit_change(struct throtl_data *td) " riops=%u wiops=%u", tg->bps[READ], tg->bps[WRITE], tg->iops[READ], tg->iops[WRITE]); + /* + * Restart the slices for both READ and WRITES. It + * might happen that a group's limit are dropped + * suddenly and we don't want to account recently + * dispatched IO with new low rate + */ + throtl_start_new_slice(td, tg, 0); + throtl_start_new_slice(td, tg, 1); + if (throtl_tg_on_rr(tg)) tg_update_disptime(td, tg); } @@ -821,7 +830,8 @@ throtl_schedule_delayed_work(struct throtl_data *td, unsigned long delay) struct delayed_work *dwork = &td->throtl_work; - if (total_nr_queued(td) > 0) { + /* schedule work if limits changed even if no bio is queued */ + if (total_nr_queued(td) > 0 || td->limits_changed) { /* * We might have a work scheduled to be executed in future. * Cancel that and schedule a new one. @@ -1002,6 +1012,19 @@ int blk_throtl_bio(struct request_queue *q, struct bio **biop) /* Bio is with-in rate limit of group */ if (tg_may_dispatch(td, tg, bio, NULL)) { throtl_charge_bio(tg, bio); + + /* + * We need to trim slice even when bios are not being queued + * otherwise it might happen that a bio is not queued for + * a long time and slice keeps on extending and trim is not + * called for a long time. Now if limits are reduced suddenly + * we take into account all the IO dispatched so far at new + * low rate and * newly queued IO gets a really long dispatch + * time. + * + * So keep on trimming slice even if bio is not queued. + */ + throtl_trim_slice(td, tg, rw); goto out; } -- cgit v1.1 From 62a37f6badd1ac97ba07d543b5d4be2f9cb17217 Mon Sep 17 00:00:00 2001 From: Justin TerAvest Date: Wed, 23 Mar 2011 08:25:44 +0100 Subject: cfq-iosched: Don't clear queue stats when preempt. For v2, I added back lines to cfq_preempt_queue() that were removed during updates for accounting unaccounted_time. Thanks for pointing out that I'd missed these, Vivek. Previous commit "cfq-iosched: Don't set active queue in preempt" wrongly cleared stats for preempting queues when it shouldn't have, because when we choose a queue to preempt, it still isn't necessarily scheduled next. Thanks to Vivek Goyal for figuring this out and understanding how the preemption code works. Signed-off-by: Justin TerAvest Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 39 +++++++++++++++++---------------------- 1 file changed, 17 insertions(+), 22 deletions(-) (limited to 'block') diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 69208d7..fea1b5a 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1620,33 +1620,27 @@ static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq) cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg); } -static void cfq_clear_queue_stats(struct cfq_data *cfqd, - struct cfq_queue *cfqq) -{ - cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg); - cfqq->slice_start = 0; - cfqq->dispatch_start = jiffies; - cfqq->allocated_slice = 0; - cfqq->slice_end = 0; - cfqq->slice_dispatch = 0; - cfqq->nr_sectors = 0; - - cfq_clear_cfqq_wait_request(cfqq); - cfq_clear_cfqq_must_dispatch(cfqq); - cfq_clear_cfqq_must_alloc_slice(cfqq); - cfq_clear_cfqq_fifo_expire(cfqq); - cfq_mark_cfqq_slice_new(cfqq); - - cfq_del_timer(cfqd, cfqq); -} - static void __cfq_set_active_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) { if (cfqq) { cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d", cfqd->serving_prio, cfqd->serving_type); - cfq_clear_queue_stats(cfqd, cfqq); + cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg); + cfqq->slice_start = 0; + cfqq->dispatch_start = jiffies; + cfqq->allocated_slice = 0; + cfqq->slice_end = 0; + cfqq->slice_dispatch = 0; + cfqq->nr_sectors = 0; + + cfq_clear_cfqq_wait_request(cfqq); + cfq_clear_cfqq_must_dispatch(cfqq); + cfq_clear_cfqq_must_alloc_slice(cfqq); + cfq_clear_cfqq_fifo_expire(cfqq); + cfq_mark_cfqq_slice_new(cfqq); + + cfq_del_timer(cfqd, cfqq); } cfqd->active_queue = cfqq; @@ -3339,7 +3333,8 @@ static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) cfq_service_tree_add(cfqd, cfqq, 1); - cfq_clear_queue_stats(cfqd, cfqq); + cfqq->slice_end = 0; + cfq_mark_cfqq_slice_new(cfqq); } /* -- cgit v1.1 From c4ade94fc00f8b34589719d8a347f658b6d3951e Mon Sep 17 00:00:00 2001 From: "Li, Shaohua" Date: Wed, 23 Mar 2011 08:30:34 +0100 Subject: cfq-iosched: removing unnecessary think time checking Removing think time checking. A high thinktime queue might means the queue dispatches several requests and then do away. Limitting such queue seems meaningless. And also this can simplify code. This is suggested by Vivek. Signed-off-by: Shaohua Li Acked-by: Vivek Goyal Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) (limited to 'block') diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index fea1b5a..7785169 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -2417,19 +2417,14 @@ static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) return false; /* - * If there is only one sync queue, and its think time is - * small, we can ignore async queue here and give the sync + * If there is only one sync queue + * we can ignore async queue here and give the sync * queue no dispatch limit. The reason is a sync queue can * preempt async queue, limiting the sync queue doesn't make * sense. This is useful for aiostress test. */ - if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1) { - struct cfq_io_context *cic = RQ_CIC(cfqq->next_rq); - - if (sample_valid(cic->ttime_samples) && - cic->ttime_mean < cfqd->cfq_slice_idle) - promote_sync = true; - } + if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1) + promote_sync = true; /* * We have other queues, don't allow more IO from this one -- cgit v1.1