lkml.org 
[lkml]   [2015]   [Jan]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2] mm: vmscan: fix the page state calculation in too_many_isolated
On 01/26/2015 10:58 PM, Michal Hocko wrote:
> On Sat 17-01-15 13:48:34, Christoph Lameter wrote:
>> On Sat, 17 Jan 2015, Vinayak Menon wrote:
>>
>>> which had not updated the vmstat_diff. This CPU was in idle for around 30
>>> secs. When I looked at the tvec base for this CPU, the timer associated with
>>> vmstat_update had its expiry time less than current jiffies. This timer had
>>> its deferrable flag set, and was tied to the next non-deferrable timer in the
>>
>> We can remove the deferrrable flag now since the vmstat threads are only
>> activated as necessary with the recent changes. Looks like this could fix
>> your issue?
>
> OK, I have checked the history and the deferrable behavior has been
> introduced by 39bf6270f524 (VM statistics: Make timer deferrable) which
> hasn't offered any numbers which would justify the change. So I think it
> would be a good idea to revert this one as it can clearly cause issues.
>
> Could you retest with this change? It still wouldn't help with the
> highly overloaded workqueues but that sounds like a bigger change and
> this one sounds like quite safe to me so it is a good start.

Sure, I can retest.
Even without highly overloaded workqueues, there can be a delay of HZ in
updating the counters. This means reclaim path can be blocked for a
second or more, when there aren't really any isolated pages. So we need
the fix in too_many_isolated also right ?


--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a
member of the Code Aurora Forum, hosted by The Linux Foundation


\
 
 \ /
  Last update: 2015-01-27 11:41    [W:0.126 / U:0.880 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site