In newer barrier codes, raise_barrier waits if conf->nr_pending[idx] is not zero. After all the conditions are true, the resync request can go on be handling. But it adds conf->nr_pending[idx] again. The next resync request hit the same bucket idx need to wait the resync request which is submitted before. The performance of resync/recovery is degraded. I did some tests: 1. Before removing the codes, the resync performance is: Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await r_await w_await svctm %util sdc 0.00 0.00 0.00 164.00 0.00 10.13 126.46 0.95 5.80 0.00 5.80 5.82 95.40 sdb 0.00 0.00 163.00 2.00 10.19 0.00 126.47 0.04 0.25 0.18 5.50 0.25 4.10 2. After removing the codes, the resync performance is: Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await r_await w_await svctm %util sdc 0.00 2164.00 0.00 751.00 0.00 182.06 496.49 7.49 9.95 0.00 9.95 1.33 100.00 sdb 2162.00 0.00 752.00 0.00 182.25 0.00 496.34 0.56 0.74 0.74 0.00 0.65 48.80 Signed-off-by: Xiao Ni <xni@xxxxxxxxxx> --- drivers/md/raid1.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index a34f587..48567ea 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -869,7 +869,6 @@ static void raise_barrier(struct r1conf *conf, sector_t sector_nr) atomic_read(&conf->barrier[idx]) < RESYNC_DEPTH, conf->resync_lock); - atomic_inc(&conf->nr_pending[idx]); spin_unlock_irq(&conf->resync_lock); } @@ -880,7 +879,6 @@ static void lower_barrier(struct r1conf *conf, sector_t sector_nr) BUG_ON(atomic_read(&conf->barrier[idx]) <= 0); atomic_dec(&conf->barrier[idx]); - atomic_dec(&conf->nr_pending[idx]); wake_up(&conf->wait_barrier); } -- 2.7.4 -- 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
