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block: remove artifical max_hw_sectors cap

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Set max_sectors to the value the drivers provides as hardware limit by
default.  Linux had proper I/O throttling for a long time and doesn't
rely on a artifically small maximum I/O size anymore.  By not limiting
the I/O size by default we remove an annoying tuning step required for
most Linux installation.

Note that both the user, and if absolutely required the driver can still
impose a limit for FS requests below max_hw_sectors_kb.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Christoph Hellwig 2014-09-06 16:08:05 -07:00 committed by Jens Axboe
parent c2661b8060
commit 34b48db66e
3 changed files with 2 additions and 5 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

4
block/blk-settings.c
View file

@ -257,9 +257,7 @@ void blk_limits_max_hw_sectors(struct queue_limits *limits, unsigned int max_hw_
__func__, max_hw_sectors);
}
limits->max_hw_sectors = max_hw_sectors;
limits->max_sectors = min_t(unsigned int, max_hw_sectors,
BLK_DEF_MAX_SECTORS);
limits->max_sectors = limits->max_hw_sectors = max_hw_sectors;
}
EXPORT_SYMBOL(blk_limits_max_hw_sectors);

2
drivers/block/aoe/aoeblk.c
View file

@ -395,7 +395,7 @@ aoeblk_gdalloc(void *vp)
WARN_ON(d->flags & DEVFL_TKILL);
WARN_ON(d->gd);
WARN_ON(d->flags & DEVFL_UP);
blk_queue_max_hw_sectors(q, BLK_DEF_MAX_SECTORS);
blk_queue_max_hw_sectors(q, 1024);
q->backing_dev_info.name = "aoe";
q->backing_dev_info.ra_pages = READ_AHEAD / PAGE_CACHE_SIZE;
d->bufpool = mp;

1
include/linux/blkdev.h
View file

@ -1186,7 +1186,6 @@ 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_MAX_SEGMENT_SIZE = 65536,
BLK_SEG_BOUNDARY_MASK = 0xFFFFFFFFUL,
};