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| author | Tejun Heo <tj@kernel.org> | 2016-05-27 21:34:46 +0300 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2016-05-30 17:54:40 +0300 |
| commit | 62a584fe05eef1f80ed49a286a29328f1a224fb9 (patch) | |
| tree | cf34bae00e267a9e5fb94a70d7f24f893d325e6b /block/blk-mq.c | |
| parent | b02b1fbdd338f70e49efa9ca9899214134526701 (diff) | |
| download | linux-62a584fe05eef1f80ed49a286a29328f1a224fb9.tar.xz | |
writeback: use higher precision calculation in domain_dirty_limits()
As vm.dirty_[background_]bytes can't be applied verbatim to multiple
cgroup writeback domains, they get converted to percentages in
domain_dirty_limits() and applied the same way as
vm.dirty_[background]ratio. However, if the specified bytes is lower
than 1% of available memory, the calculated ratios become zero and the
writeback domain gets throttled constantly.
Fix it by using per-PAGE_SIZE instead of percentage for ratio
calculations. Also, the updated DIV_ROUND_UP() usages now should
yield 1/4096 (0.0244%) as the minimum ratio as long as the specified
bytes are above zero.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Miao Xie <miaoxie@huawei.com>
Link: http://lkml.kernel.org/g/57333E75.3080309@huawei.com
Cc: stable@vger.kernel.org # v4.2+
Fixes: 9fc3a43e1757 ("writeback: separate out domain_dirty_limits()")
Reviewed-by: Jan Kara <jack@suse.cz>
Adjusted comment based on Jan's suggestion.
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block/blk-mq.c')
0 files changed, 0 insertions, 0 deletions