Commit 30e2bc08 authored by Jeff Moyer's avatar Jeff Moyer Committed by Jens Axboe
Browse files

Revert "block: remove artifical max_hw_sectors cap" 



This reverts commit 34b48db6.
That commit caused performance regressions for streaming I/O
workloads on a number of different storage devices, from
SATA disks to external RAID arrays.  It also managed to
trip up some buggy firmware in at least one drive, causing
data corruption.

The next patch will bump the default max_sectors_kb value to
1280, which will accommodate a 10-data-disk stripe write
with chunk size 128k.  In the testing I've done using iozone,
fio, and aio-stress, a value of 1280 does not show a big
performance difference from 512.  This will hopefully still
help the software RAID setup that Christoph saw the original
performance gains with while still not regressing other
storage configurations.

Signed-off-by: default avatarJeff Moyer <jmoyer@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 0048b483

block/blk-settings.c

+3 −1
Original line number Original line Diff line number Diff line
@@ -236,7 +236,9 @@ void blk_limits_max_hw_sectors(struct queue_limits *limits, unsigned int max_hw_ 
		       __func__, max_hw_sectors);

		       __func__, max_hw_sectors);

	}

	}





	limits->max_sectors = limits->max_hw_sectors = max_hw_sectors;

	limits->max_hw_sectors = max_hw_sectors;

	limits->max_sectors = min_t(unsigned int, max_hw_sectors,

				    BLK_DEF_MAX_SECTORS);

}

}

EXPORT_SYMBOL(blk_limits_max_hw_sectors);

EXPORT_SYMBOL(blk_limits_max_hw_sectors);

drivers/block/aoe/aoeblk.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -395,7 +395,7 @@ aoeblk_gdalloc(void *vp) 
	WARN_ON(d->flags & DEVFL_TKILL);

	WARN_ON(d->flags & DEVFL_TKILL);

	WARN_ON(d->gd);

	WARN_ON(d->gd);

	WARN_ON(d->flags & DEVFL_UP);

	WARN_ON(d->flags & DEVFL_UP);

	blk_queue_max_hw_sectors(q, 1024);

	blk_queue_max_hw_sectors(q, BLK_DEF_MAX_SECTORS);

	q->backing_dev_info.name = "aoe";

	q->backing_dev_info.name = "aoe";

	q->backing_dev_info.ra_pages = READ_AHEAD / PAGE_CACHE_SIZE;

	q->backing_dev_info.ra_pages = READ_AHEAD / PAGE_CACHE_SIZE;

	d->bufpool = mp;

	d->bufpool = mp;

include/linux/blkdev.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -1132,6 +1132,7 @@ extern int blk_verify_command(unsigned char *cmd, fmode_t has_write_perm); 
enum blk_default_limits {

enum blk_default_limits {

	BLK_MAX_SEGMENTS	= 128,

	BLK_MAX_SEGMENTS	= 128,

	BLK_SAFE_MAX_SECTORS	= 255,

	BLK_SAFE_MAX_SECTORS	= 255,

	BLK_DEF_MAX_SECTORS	= 1024,

	BLK_MAX_SEGMENT_SIZE	= 65536,

	BLK_MAX_SEGMENT_SIZE	= 65536,

	BLK_SEG_BOUNDARY_MASK	= 0xFFFFFFFFUL,

	BLK_SEG_BOUNDARY_MASK	= 0xFFFFFFFFUL,

};

};

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