md:Add blk_plug in sync_thread.
Add blk_plug in sync_thread will increase the performance of sync.
Because sync_thread did not blk_plug,so when raid sync, the bio merge
not well.
Testing environment:
SATA controller: Intel Corporation 82801JI (ICH10 Family) SATA AHCI
Controller.
OS:Linux xxx 3.5.0-rc2+ #340 SMP Tue Jun 12 09:00:25 CST 2012
x86_64 x86_64 x86_64 GNU/Linux.
RAID5: four ST31000524NS disk.
Without blk_plug:recovery speed about 63M/Sec;
Add blk_plug:recovery speed about 120M/Sec.
Using blktrace:
blktrace -d /dev/sdb -w 60 -o -|blkparse -i -
without blk_plug:
Total (8,16):
Reads Queued: 309811, 1239MiB Writes Queued: 0, 0KiB
Read Dispatches: 283583, 1189MiB Write Dispatches: 0, 0KiB
Reads Requeued: 0 Writes Requeued: 0
Reads Completed: 273351, 1149MiB Writes Completed: 0, 0KiB
Read Merges: 23533, 94132KiB Write Merges: 0, 0KiB
IO unplugs: 0 Timer unplugs: 0
add blk_plug:
Total (8,16):
Reads Queued: 428697, 1714MiB Writes Queued: 0, 0KiB
Read Dispatches: 3954, 1714MiB Write Dispatches: 0, 0KiB
Reads Requeued: 0 Writes Requeued: 0
Reads Completed: 3956, 1715MiB Writes Completed: 0, 0KiB
Read Merges: 424743, 1698MiB Write Merges: 0, 0KiB
IO unplugs: 0 Timer unplugs: 3384
The ratio of merge will be markedly increased.
Signed-off-by: majianpeng <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 1c2f904..973aa84 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -7298,6 +7298,7 @@
int skipped = 0;
struct md_rdev *rdev;
char *desc;
+ struct blk_plug plug;
/* just incase thread restarts... */
if (test_bit(MD_RECOVERY_DONE, &mddev->recovery))
@@ -7447,6 +7448,7 @@
}
mddev->curr_resync_completed = j;
+ blk_start_plug(&plug);
while (j < max_sectors) {
sector_t sectors;
@@ -7552,6 +7554,7 @@
* this also signals 'finished resyncing' to md_stop
*/
out:
+ blk_finish_plug(&plug);
wait_event(mddev->recovery_wait, !atomic_read(&mddev->recovery_active));
/* tell personality that we are finished */