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author | phk <phk@FreeBSD.org> | 2002-09-20 14:14:37 +0000 |
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committer | phk <phk@FreeBSD.org> | 2002-09-20 14:14:37 +0000 |
commit | 7fd38535eae3b6a4d4995a5d64312946ac90c975 (patch) | |
tree | 3a943971e7e89a1029824f9f9d07d4300238f212 /sys/kern/subr_disk.c | |
parent | 868209c8920da6141c8bdc1603136cfebd8b224f (diff) | |
download | FreeBSD-src-7fd38535eae3b6a4d4995a5d64312946ac90c975.zip FreeBSD-src-7fd38535eae3b6a4d4995a5d64312946ac90c975.tar.gz |
Make FreeBSD "struct disklabel" agnostic, step 312 of 723:
Rename bioqdisksort() to bioq_disksort().
Keep a #define around to avoid changing all diskdrivers right now.
Move it from subr_disklabel.c to subr_disk.c.
Move prototype from <sys/disklabel.h> to <sys/bio.h>
Sponsored by: DARPA and NAI Labs.
Diffstat (limited to 'sys/kern/subr_disk.c')
-rw-r--r-- | sys/kern/subr_disk.c | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/sys/kern/subr_disk.c b/sys/kern/subr_disk.c index 801eaaf..388ea79 100644 --- a/sys/kern/subr_disk.c +++ b/sys/kern/subr_disk.c @@ -469,3 +469,153 @@ disk_err(struct bio *bp, const char *what, int blkdone, int nl) if (nl) printf("\n"); } + +#ifdef notquite +/* + * Mutex to use when delaying niced I/O bound processes in bioq_disksort(). + */ +static struct mtx dksort_mtx; +static void +dksort_init(void) +{ + + mtx_init(&dksort_mtx, "dksort", NULL, MTX_DEF); +} +SYSINIT(dksort, SI_SUB_DRIVERS, SI_ORDER_MIDDLE, dksort_init, NULL) +#endif + +/* + * Seek sort for disks. + * + * The buf_queue keep two queues, sorted in ascending block order. The first + * queue holds those requests which are positioned after the current block + * (in the first request); the second, which starts at queue->switch_point, + * holds requests which came in after their block number was passed. Thus + * we implement a one way scan, retracting after reaching the end of the drive + * to the first request on the second queue, at which time it becomes the + * first queue. + * + * A one-way scan is natural because of the way UNIX read-ahead blocks are + * allocated. + */ + +void +bioq_disksort(bioq, bp) + struct bio_queue_head *bioq; + struct bio *bp; +{ + struct bio *bq; + struct bio *bn; + struct bio *be; + +#ifdef notquite + struct thread *td = curthread; + + if (td && td->td_ksegrp->kg_nice > 0) { + TAILQ_FOREACH(bn, &bioq->queue, bio_queue) + if (BIOTOBUF(bp)->b_vp != BIOTOBUF(bn)->b_vp) + break; + if (bn != NULL) { + mtx_lock(&dksort_mtx); + msleep(&dksort_mtx, &dksort_mtx, + PPAUSE | PCATCH | PDROP, "ioslow", + td->td_ksegrp->kg_nice); + } + } +#endif + if (!atomic_cmpset_int(&bioq->busy, 0, 1)) + panic("Recursing in bioq_disksort()"); + be = TAILQ_LAST(&bioq->queue, bio_queue); + /* + * If the queue is empty or we are an + * ordered transaction, then it's easy. + */ + if ((bq = bioq_first(bioq)) == NULL) { + bioq_insert_tail(bioq, bp); + bioq->busy = 0; + return; + } else if (bioq->insert_point != NULL) { + + /* + * A certain portion of the list is + * "locked" to preserve ordering, so + * we can only insert after the insert + * point. + */ + bq = bioq->insert_point; + } else { + + /* + * If we lie before the last removed (currently active) + * request, and are not inserting ourselves into the + * "locked" portion of the list, then we must add ourselves + * to the second request list. + */ + if (bp->bio_pblkno < bioq->last_pblkno) { + + bq = bioq->switch_point; + /* + * If we are starting a new secondary list, + * then it's easy. + */ + if (bq == NULL) { + bioq->switch_point = bp; + bioq_insert_tail(bioq, bp); + bioq->busy = 0; + return; + } + /* + * If we lie ahead of the current switch point, + * insert us before the switch point and move + * the switch point. + */ + if (bp->bio_pblkno < bq->bio_pblkno) { + bioq->switch_point = bp; + TAILQ_INSERT_BEFORE(bq, bp, bio_queue); + bioq->busy = 0; + return; + } + } else { + if (bioq->switch_point != NULL) + be = TAILQ_PREV(bioq->switch_point, + bio_queue, bio_queue); + /* + * If we lie between last_pblkno and bq, + * insert before bq. + */ + if (bp->bio_pblkno < bq->bio_pblkno) { + TAILQ_INSERT_BEFORE(bq, bp, bio_queue); + bioq->busy = 0; + return; + } + } + } + + /* + * Request is at/after our current position in the list. + * Optimize for sequential I/O by seeing if we go at the tail. + */ + if (bp->bio_pblkno > be->bio_pblkno) { + TAILQ_INSERT_AFTER(&bioq->queue, be, bp, bio_queue); + bioq->busy = 0; + return; + } + + /* Otherwise, insertion sort */ + while ((bn = TAILQ_NEXT(bq, bio_queue)) != NULL) { + + /* + * We want to go after the current request if it is the end + * of the first request list, or if the next request is a + * larger cylinder than our request. + */ + if (bn == bioq->switch_point + || bp->bio_pblkno < bn->bio_pblkno) + break; + bq = bn; + } + TAILQ_INSERT_AFTER(&bioq->queue, bq, bp, bio_queue); + bioq->busy = 0; +} + + |