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| author | Shaohua Li <shli@kernel.org> | 2014-04-09 11:25:47 +0800 |
|---|---|---|
| committer | NeilBrown <neilb@suse.de> | 2014-04-09 14:42:38 +1000 |
| commit | 27c0f68f0745218cec70f19ba7560c8c5fc3f817 (patch) | |
| tree | c8f8fcefca0ced4a5e990a94094c2c2b70ee2c55 /drivers/md | |
| parent | e2f23b606b94f28a8febd5aa715df697d80b018e (diff) | |
| download | linux-27c0f68f0745218cec70f19ba7560c8c5fc3f817.tar.gz linux-27c0f68f0745218cec70f19ba7560c8c5fc3f817.tar.bz2 linux-27c0f68f0745218cec70f19ba7560c8c5fc3f817.zip | |
raid5: make_request does less prepare wait
In NUMA machine, prepare_to_wait/finish_wait in make_request exposes a
lot of contention for sequential workload (or big request size
workload). For such workload, each bio includes several stripes. So we
can just do prepare_to_wait/finish_wait once for the whold bio instead
of every stripe. This reduces the lock contention completely for such
workload. Random workload might have the similar lock contention too,
but I didn't see it yet, maybe because my stroage is still not fast
enough.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/raid5.c | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 16f5c21963db..a904a2c80fc8 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -4552,6 +4552,8 @@ static void make_request(struct mddev *mddev, struct bio * bi) struct stripe_head *sh; const int rw = bio_data_dir(bi); int remaining; + DEFINE_WAIT(w); + bool do_prepare; if (unlikely(bi->bi_rw & REQ_FLUSH)) { md_flush_request(mddev, bi); @@ -4575,15 +4577,18 @@ static void make_request(struct mddev *mddev, struct bio * bi) bi->bi_next = NULL; bi->bi_phys_segments = 1; /* over-loaded to count active stripes */ + prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE); for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) { - DEFINE_WAIT(w); int previous; int seq; + do_prepare = false; retry: seq = read_seqcount_begin(&conf->gen_lock); previous = 0; - prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE); + if (do_prepare) + prepare_to_wait(&conf->wait_for_overlap, &w, + TASK_UNINTERRUPTIBLE); if (unlikely(conf->reshape_progress != MaxSector)) { /* spinlock is needed as reshape_progress may be * 64bit on a 32bit platform, and so it might be @@ -4604,6 +4609,7 @@ static void make_request(struct mddev *mddev, struct bio * bi) : logical_sector >= conf->reshape_safe) { spin_unlock_irq(&conf->device_lock); schedule(); + do_prepare = true; goto retry; } } @@ -4640,6 +4646,7 @@ static void make_request(struct mddev *mddev, struct bio * bi) if (must_retry) { release_stripe(sh); schedule(); + do_prepare = true; goto retry; } } @@ -4663,8 +4670,10 @@ static void make_request(struct mddev *mddev, struct bio * bi) prepare_to_wait(&conf->wait_for_overlap, &w, TASK_INTERRUPTIBLE); if (logical_sector >= mddev->suspend_lo && - logical_sector < mddev->suspend_hi) + logical_sector < mddev->suspend_hi) { schedule(); + do_prepare = true; + } goto retry; } @@ -4677,9 +4686,9 @@ static void make_request(struct mddev *mddev, struct bio * bi) md_wakeup_thread(mddev->thread); release_stripe(sh); schedule(); + do_prepare = true; goto retry; } - finish_wait(&conf->wait_for_overlap, &w); set_bit(STRIPE_HANDLE, &sh->state); clear_bit(STRIPE_DELAYED, &sh->state); if ((bi->bi_rw & REQ_SYNC) && @@ -4689,10 +4698,10 @@ static void make_request(struct mddev *mddev, struct bio * bi) } else { /* cannot get stripe for read-ahead, just give-up */ clear_bit(BIO_UPTODATE, &bi->bi_flags); - finish_wait(&conf->wait_for_overlap, &w); break; } } + finish_wait(&conf->wait_for_overlap, &w); remaining = raid5_dec_bi_active_stripes(bi); if (remaining == 0) { |