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block: Optimal I/O limit wrapper

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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>
This commit is contained in:
Martin K. Petersen 2009-09-11 21:54:52 +02:00 committed by Jens Axboe
parent 06d2188644
commit 3c5820c743
3 changed files with 22 additions and 2 deletions
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21
block/blk-settings.c
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@ -427,6 +427,25 @@ 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
@ -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);

2
drivers/md/dm-stripe.c
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@ -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 = {

1
include/linux/blkdev.h
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@ -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,