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| author | Martin K. Petersen <martin.petersen@oracle.com> | 2009-09-11 21:54:52 +0200 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2009-09-14 08:24:52 +0200 |
| commit | 3c5820c743479285ce2678fd3c12b1fd39fe998f (patch) | |
| tree | 8f6b3980f5e8da4912b44eee4688d51ce12c97a3 | |
| parent | 06d2188644c85c56d243efab914f368d1d23c4a3 (diff) | |
| download | lwn-3c5820c743479285ce2678fd3c12b1fd39fe998f.tar.gz lwn-3c5820c743479285ce2678fd3c12b1fd39fe998f.zip | |
block: Optimal I/O limit wrapper
Implement blk_limits_io_opt() and make blk_queue_io_opt() a wrapper
around it. DM needs this to avoid poking at the queue_limits directly.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
| -rw-r--r-- | block/blk-settings.c | 21 | ||||
| -rw-r--r-- | drivers/md/dm-stripe.c | 2 | ||||
| -rw-r--r-- | include/linux/blkdev.h | 1 |
3 files changed, 22 insertions, 2 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c index 476d87065073..83413ff83739 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -428,6 +428,25 @@ void blk_queue_io_min(struct request_queue *q, unsigned int min) EXPORT_SYMBOL(blk_queue_io_min); /** + * blk_limits_io_opt - set optimal request size for a device + * @limits: the queue limits + * @opt: smallest I/O size in bytes + * + * Description: + * Storage devices may report an optimal I/O size, which is the + * device's preferred unit for sustained I/O. This is rarely reported + * for disk drives. For RAID arrays it is usually the stripe width or + * the internal track size. A properly aligned multiple of + * optimal_io_size is the preferred request size for workloads where + * sustained throughput is desired. + */ +void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt) +{ + limits->io_opt = opt; +} +EXPORT_SYMBOL(blk_limits_io_opt); + +/** * blk_queue_io_opt - set optimal request size for the queue * @q: the request queue for the device * @opt: optimal request size in bytes @@ -442,7 +461,7 @@ EXPORT_SYMBOL(blk_queue_io_min); */ void blk_queue_io_opt(struct request_queue *q, unsigned int opt) { - q->limits.io_opt = opt; + blk_limits_io_opt(&q->limits, opt); } EXPORT_SYMBOL(blk_queue_io_opt); diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c index fde658ccbcec..e0efc1adcaff 100644 --- a/drivers/md/dm-stripe.c +++ b/drivers/md/dm-stripe.c @@ -336,7 +336,7 @@ static void stripe_io_hints(struct dm_target *ti, unsigned chunk_size = (sc->chunk_mask + 1) << 9; blk_limits_io_min(limits, chunk_size); - limits->io_opt = chunk_size * sc->stripes; + blk_limits_io_opt(limits, chunk_size * sc->stripes); } static struct target_type stripe_target = { diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 8bf1a10e4d88..86c2bdff3b89 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -935,6 +935,7 @@ extern void blk_queue_alignment_offset(struct request_queue *q, unsigned int alignment); extern void blk_limits_io_min(struct queue_limits *limits, unsigned int min); extern void blk_queue_io_min(struct request_queue *q, unsigned int min); +extern void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt); extern void blk_queue_io_opt(struct request_queue *q, unsigned int opt); extern void blk_set_default_limits(struct queue_limits *lim); extern int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, |