In raid 0 case, a big discard request is divided into several small requests
in chunk_size unit. Such requests can be merged in low layer if we have
correct plug added. This should improve the performance a little bit.
raid 10 case doesn't matter, as we dispatch request in a separate thread
and there is plug there.
Signed-off-by: Shaohua Li <shli@xxxxxxxxxxxx>
---
block/blk-lib.c | 3 +++
1 file changed, 3 insertions(+)
Index: linux/block/blk-lib.c
===================================================================
--- linux.orig/block/blk-lib.c 2012-03-09 16:56:41.043790011 +0800
+++ linux/block/blk-lib.c 2012-03-12 10:21:38.716609525 +0800
@@ -47,6 +47,7 @@ int blkdev_issue_discard(struct block_de
struct bio_batch bb;
struct bio *bio;
int ret = 0;
+ struct blk_plug plug;
if (!q)
return -ENXIO;
@@ -78,6 +79,7 @@ int blkdev_issue_discard(struct block_de
bb.flags = 1 << BIO_UPTODATE;
bb.wait = &wait;
+ blk_start_plug(&plug);
while (nr_sects) {
bio = bio_alloc(gfp_mask, 1);
if (!bio) {
@@ -102,6 +104,7 @@ int blkdev_issue_discard(struct block_de
atomic_inc(&bb.done);
submit_bio(type, bio);
}
+ blk_finish_plug(&plug);
/* Wait for bios in-flight */
if (!atomic_dec_and_test(&bb.done))
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
