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Diffstat (limited to 'drivers/md/raid1.c')
-rw-r--r--drivers/md/raid1.c34
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)