diff options
| author | Raz Ben-Jehuda(caro) <raziebe@gmail.com> | 2006-12-10 02:20:45 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.osdl.org> | 2006-12-10 09:57:20 -0800 |
| commit | 23032a0eb97c8eaae8ac9d17373b53b19d0f5413 (patch) | |
| tree | 7021309ed7a591c6ae93f7347fb23482cea85163 /drivers/md/raid5.c | |
| parent | 0d4ca600fcf5c5f3a0c195ccf37e989b83451dd4 (diff) | |
[PATCH] md: define raid5_mergeable_bvec
This will encourage read request to be on only one device, so we will often be
able to bypass the cache for read requests.
Signed-off-by: Neil Brown <neilb@suse.de>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'drivers/md/raid5.c')
| -rw-r--r-- | drivers/md/raid5.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 52914d5cec7..b86ceba04f6 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -2611,6 +2611,28 @@ static int raid5_congested(void *data, int bits) return 0; } +/* We want read requests to align with chunks where possible, + * but write requests don't need to. + */ +static int raid5_mergeable_bvec(request_queue_t *q, struct bio *bio, struct bio_vec *biovec) +{ + mddev_t *mddev = q->queuedata; + sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev); + int max; + unsigned int chunk_sectors = mddev->chunk_size >> 9; + unsigned int bio_sectors = bio->bi_size >> 9; + + if (bio_data_dir(bio)) + return biovec->bv_len; /* always allow writes to be mergeable */ + + max = (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9; + if (max < 0) max = 0; + if (max <= biovec->bv_len && bio_sectors == 0) + return biovec->bv_len; + else + return max; +} + static int make_request(request_queue_t *q, struct bio * bi) { mddev_t *mddev = q->queuedata; @@ -3320,6 +3342,8 @@ static int run(mddev_t *mddev) mddev->array_size = mddev->size * (conf->previous_raid_disks - conf->max_degraded); + blk_queue_merge_bvec(mddev->queue, raid5_mergeable_bvec); + return 0; abort: if (conf) { |