From 598971bfbdfdc8701337dc1636c7919c44699914 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 19 Mar 2012 15:10:58 -0700 Subject: cfq: don't use icq_get_changed() cfq caches the associated cfqq's for a given cic. The cache needs to be flushed if the cic's ioprio or blkcg has changed. It is currently done by requiring the changing action to set the respective ICQ_*_CHANGED bit in the icq and testing it from cfq_set_request(), which involves iterating through all the affected icqs. All cfq wants to know is whether ioprio and/or blkcg have changed since the last flush and can be easily achieved by just remembering the current ioprio and blkcg ID in cic. This patch adds cic->{ioprio|blkcg_id}, updates all ioprio users to use the remembered value instead, and updates cfq_set_request() path such that, instead of using icq_get_changed(), the current values are compared against the remembered ones and trigger appropriate flush action if not. Condition tests are moved inside both _changed functions which are now named check_ioprio_changed() and check_blkcg_changed(). ioprio.h::task_ioprio*() can't be used anymore and replaced with open-coded IOPRIO_CLASS_NONE case in cfq_async_queue_prio(). Signed-off-by: Tejun Heo Cc: Vivek Goyal Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 63 ++++++++++++++++++++++++++++++++++------------------- 1 file changed, 40 insertions(+), 23 deletions(-) (limited to 'block/cfq-iosched.c') diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 9e8624e..7c3893d 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -218,6 +218,10 @@ struct cfq_io_cq { struct io_cq icq; /* must be the first member */ struct cfq_queue *cfqq[2]; struct cfq_ttime ttime; + int ioprio; /* the current ioprio */ +#ifdef CONFIG_CFQ_GROUP_IOSCHED + uint64_t blkcg_id; /* the current blkcg ID */ +#endif }; /* @@ -2568,7 +2572,7 @@ static void cfq_init_prio_data(struct cfq_queue *cfqq, struct cfq_io_cq *cic) if (!cfq_cfqq_prio_changed(cfqq)) return; - ioprio_class = IOPRIO_PRIO_CLASS(cic->icq.ioc->ioprio); + ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio); switch (ioprio_class) { default: printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); @@ -2580,11 +2584,11 @@ static void cfq_init_prio_data(struct cfq_queue *cfqq, struct cfq_io_cq *cic) cfqq->ioprio_class = task_nice_ioclass(tsk); break; case IOPRIO_CLASS_RT: - cfqq->ioprio = task_ioprio(cic->icq.ioc); + cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio); cfqq->ioprio_class = IOPRIO_CLASS_RT; break; case IOPRIO_CLASS_BE: - cfqq->ioprio = task_ioprio(cic->icq.ioc); + cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio); cfqq->ioprio_class = IOPRIO_CLASS_BE; break; case IOPRIO_CLASS_IDLE: @@ -2602,12 +2606,17 @@ static void cfq_init_prio_data(struct cfq_queue *cfqq, struct cfq_io_cq *cic) cfq_clear_cfqq_prio_changed(cfqq); } -static void changed_ioprio(struct cfq_io_cq *cic, struct bio *bio) +static void check_ioprio_changed(struct cfq_io_cq *cic, struct bio *bio) { + int ioprio = cic->icq.ioc->ioprio; struct cfq_data *cfqd = cic_to_cfqd(cic); struct cfq_queue *cfqq; - if (unlikely(!cfqd)) + /* + * Check whether ioprio has changed. The condition may trigger + * spuriously on a newly created cic but there's no harm. + */ + if (unlikely(!cfqd) || likely(cic->ioprio == ioprio)) return; cfqq = cic->cfqq[BLK_RW_ASYNC]; @@ -2624,6 +2633,8 @@ static void changed_ioprio(struct cfq_io_cq *cic, struct bio *bio) cfqq = cic->cfqq[BLK_RW_SYNC]; if (cfqq) cfq_mark_cfqq_prio_changed(cfqq); + + cic->ioprio = ioprio; } static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq, @@ -2647,17 +2658,24 @@ static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq, } #ifdef CONFIG_CFQ_GROUP_IOSCHED -static void changed_cgroup(struct cfq_io_cq *cic) +static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { - struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1); struct cfq_data *cfqd = cic_to_cfqd(cic); - struct request_queue *q; + struct cfq_queue *sync_cfqq; + uint64_t id; - if (unlikely(!cfqd)) - return; + rcu_read_lock(); + id = bio_blkio_cgroup(bio)->id; + rcu_read_unlock(); - q = cfqd->queue; + /* + * Check whether blkcg has changed. The condition may trigger + * spuriously on a newly created cic but there's no harm. + */ + if (unlikely(!cfqd) || likely(cic->blkcg_id == id)) + return; + sync_cfqq = cic_to_cfqq(cic, 1); if (sync_cfqq) { /* * Drop reference to sync queue. A new sync queue will be @@ -2667,7 +2685,11 @@ static void changed_cgroup(struct cfq_io_cq *cic) cic_set_cfqq(cic, NULL, 1); cfq_put_queue(sync_cfqq); } + + cic->blkcg_id = id; } +#else +static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { } #endif /* CONFIG_CFQ_GROUP_IOSCHED */ static struct cfq_queue * @@ -2731,6 +2753,9 @@ cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) switch (ioprio_class) { case IOPRIO_CLASS_RT: return &cfqd->async_cfqq[0][ioprio]; + case IOPRIO_CLASS_NONE: + ioprio = IOPRIO_NORM; + /* fall through */ case IOPRIO_CLASS_BE: return &cfqd->async_cfqq[1][ioprio]; case IOPRIO_CLASS_IDLE: @@ -2744,8 +2769,8 @@ static struct cfq_queue * cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic, struct bio *bio, gfp_t gfp_mask) { - const int ioprio = task_ioprio(cic->icq.ioc); - const int ioprio_class = task_ioprio_class(cic->icq.ioc); + const int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio); + const int ioprio = IOPRIO_PRIO_DATA(cic->ioprio); struct cfq_queue **async_cfqq = NULL; struct cfq_queue *cfqq = NULL; @@ -3303,21 +3328,13 @@ cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio, const int rw = rq_data_dir(rq); const bool is_sync = rq_is_sync(rq); struct cfq_queue *cfqq; - unsigned int changed; might_sleep_if(gfp_mask & __GFP_WAIT); spin_lock_irq(q->queue_lock); - /* handle changed notifications */ - changed = icq_get_changed(&cic->icq); - if (unlikely(changed & ICQ_IOPRIO_CHANGED)) - changed_ioprio(cic, bio); -#ifdef CONFIG_CFQ_GROUP_IOSCHED - if (unlikely(changed & ICQ_CGROUP_CHANGED)) - changed_cgroup(cic); -#endif - + check_ioprio_changed(cic, bio); + check_blkcg_changed(cic, bio); new_queue: cfqq = cic_to_cfqq(cic, is_sync); if (!cfqq || cfqq == &cfqd->oom_cfqq) { -- cgit v1.1