diff options
| -rw-r--r-- | drivers/md/raid1.c | 34 |
1 files changed, 31 insertions, 3 deletions
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index fb96c0c2db40..d9869f25aa75 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -497,9 +497,11 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect const sector_t this_sector = r1_bio->sector; int sectors; int best_good_sectors; - int best_disk; + int best_disk, best_dist_disk, best_pending_disk; + int has_nonrot_disk; int disk; sector_t best_dist; + unsigned int min_pending; struct md_rdev *rdev; int choose_first; @@ -512,8 +514,12 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect retry: sectors = r1_bio->sectors; best_disk = -1; + best_dist_disk = -1; best_dist = MaxSector; + best_pending_disk = -1; + min_pending = UINT_MAX; best_good_sectors = 0; + has_nonrot_disk = 0; if (conf->mddev->recovery_cp < MaxSector && (this_sector + sectors >= conf->next_resync)) @@ -525,6 +531,7 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect sector_t dist; sector_t first_bad; int bad_sectors; + unsigned int pending; rdev = rcu_dereference(conf->mirrors[disk].rdev); if (r1_bio->bios[disk] == IO_BLOCKED @@ -583,22 +590,43 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect } else best_good_sectors = sectors; + has_nonrot_disk |= blk_queue_nonrot(bdev_get_queue(rdev->bdev)); + pending = atomic_read(&rdev->nr_pending); dist = abs(this_sector - conf->mirrors[disk].head_position); if (choose_first /* Don't change to another disk for sequential reads */ || conf->mirrors[disk].next_seq_sect == this_sector || dist == 0 /* If device is idle, use it */ - || atomic_read(&rdev->nr_pending) == 0) { + || pending == 0) { best_disk = disk; break; } + + if (min_pending > pending) { + min_pending = pending; + best_pending_disk = disk; + } + if (dist < best_dist) { best_dist = dist; - best_disk = disk; + best_dist_disk = disk; } } + /* + * If all disks are rotational, choose the closest disk. If any disk is + * non-rotational, choose the disk with less pending request even the + * disk is rotational, which might/might not be optimal for raids with + * mixed ratation/non-rotational disks depending on workload. + */ + if (best_disk == -1) { + if (has_nonrot_disk) + best_disk = best_pending_disk; + else + best_disk = best_dist_disk; + } + if (best_disk >= 0) { rdev = rcu_dereference(conf->mirrors[best_disk].rdev); if (!rdev) |