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authorMartin K. Petersen <martin.petersen@oracle.com>2009-09-11 21:54:52 +0200
committerJens Axboe <jens.axboe@oracle.com>2009-09-14 08:24:52 +0200
commit3c5820c743479285ce2678fd3c12b1fd39fe998f (patch)
tree8f6b3980f5e8da4912b44eee4688d51ce12c97a3
parent06d2188644c85c56d243efab914f368d1d23c4a3 (diff)
downloadlinux-3c5820c743479285ce2678fd3c12b1fd39fe998f.tar.bz2
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.c21
-rw-r--r--drivers/md/dm-stripe.c2
-rw-r--r--include/linux/blkdev.h1
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,