diff options
| author | Yafang Shao <laoar.shao@gmail.com> | 2017-11-15 17:33:45 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-11-15 18:21:03 -0800 |
| commit | 0f6d24f878568fac579a1962d0bf7cb9f01e0ceb (patch) | |
| tree | 5fa7529b42621ab7b1a86ec8d5f3dc01cb9d7b10 | |
| parent | 66e8b438bd5c75498cfe915c4219049eaebcb869 (diff) | |
mm/page-writeback.c: print a warning if the vm dirtiness settings are illogical
The vm direct limit setting must be set greater than vm background limit
setting. Otherwise print a warning to help the operator to figure out
that the vm dirtiness settings is in illogical state.
Link: http://lkml.kernel.org/r/1506592464-30962-1-git-send-email-laoar.shao@gmail.com
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | Documentation/sysctl/vm.txt | 7 | ||||
| -rw-r--r-- | mm/page-writeback.c | 5 |
2 files changed, 11 insertions, 1 deletions
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt index 9baf66a9ef4e..30fd16b14196 100644 --- a/Documentation/sysctl/vm.txt +++ b/Documentation/sysctl/vm.txt @@ -157,6 +157,10 @@ Note: the minimum value allowed for dirty_bytes is two pages (in bytes); any value lower than this limit will be ignored and the old configuration will be retained. +Note: the value of dirty_bytes also must be set greater than +dirty_background_bytes or the amount of memory corresponding to +dirty_background_ratio. + ============================================================== dirty_expire_centisecs @@ -176,6 +180,9 @@ generating disk writes will itself start writing out dirty data. The total available memory is not equal to total system memory. +Note: dirty_ratio must be set greater than dirty_background_ratio or +ratio corresponding to dirty_background_bytes. + ============================================================== dirty_writeback_centisecs diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 76a43c17761b..768fe4e37e6a 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -433,8 +433,11 @@ static void domain_dirty_limits(struct dirty_throttle_control *dtc) else bg_thresh = (bg_ratio * available_memory) / PAGE_SIZE; - if (bg_thresh >= thresh) + if (unlikely(bg_thresh >= thresh)) { + pr_warn("vm direct limit must be set greater than background limit.\n"); bg_thresh = thresh / 2; + } + tsk = current; if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk)) { bg_thresh += bg_thresh / 4 + global_wb_domain.dirty_limit / 32; |