block: bump BLK_DEF_MAX_SECTORS to 2560

Orabug: 22611290

A value of 2560 (1280k) will accommodate a 10-data-disk stripe
write with chunk size 128k.  In the testing I've done using
iozone, fio, and aio-stress across a number of different storage
devices, a value of 1280 does not show a big performance
difference from 512, but will hopefully help software RAID
setups using SATA disks, as reported by Christoph.

NOTE: drivers/block/aoe/aoeblk.c sets its own max_hw_sectors_kb to
BLK_DEF_MAX_SECTORS.  So, this patch essentially changes aeoblk to
Use a larger maximum sector size, and I did not test this.

Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
(cherry picked from commit d2be537c3ba3568acd79cd178327b842e60d035e)

Signed-off-by: Tariq Saeed <tariq.x.saeed@oracle.com>

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index fa986c9323c841c2e698678e40346545abb4a780..df359764d28b8f389009bcf84adbbd699339fe8d 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1186,7 +1186,7 @@ extern int blk_verify_command(unsigned char *cmd, fmode_t has_write_perm);
 enum blk_default_limits {
        BLK_MAX_SEGMENTS        = 128,
        BLK_SAFE_MAX_SECTORS    = 255,
-       BLK_DEF_MAX_SECTORS     = 1024,
+       BLK_DEF_MAX_SECTORS     = 2560,
        BLK_MAX_SEGMENT_SIZE    = 65536,
        BLK_SEG_BOUNDARY_MASK   = 0xFFFFFFFFUL,
 };