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From: Vinayak Menon <vinmenon@codeaurora.org>
To: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	akpm@linux-foundation.org, hannes@cmpxchg.org,
	vdavydov@parallels.com, mgorman@suse.de, minchan@kernel.org
Subject: Re: [PATCH v2] mm: vmscan: fix the page state calculation in too_many_isolated
Date: Tue, 27 Jan 2015 16:03:57 +0530	[thread overview]
Message-ID: <54C76995.70501@codeaurora.org> (raw)
In-Reply-To: <20150126172832.GC22681@dhcp22.suse.cz>

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

  parent reply	other threads:[~2015-01-27 10:34 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-14 11:36 Vinayak Menon
2015-01-14 16:50 ` Michal Hocko
2015-01-15 17:24   ` Vinayak Menon
2015-01-16 15:49     ` Michal Hocko
2015-01-16 17:57       ` Michal Hocko
2015-01-16 19:17         ` Christoph Lameter
2015-01-17 15:18       ` Vinayak Menon
2015-01-17 19:48         ` Christoph Lameter
2015-01-19  4:27           ` Vinayak Menon
2015-01-21 14:39             ` Michal Hocko
2015-01-22 15:16               ` Vlastimil Babka
2015-01-22 16:11               ` Christoph Lameter
2015-01-26 17:46                 ` Michal Hocko
2015-01-26 18:35                   ` Christoph Lameter
2015-01-27 10:52                     ` Michal Hocko
2015-01-27 16:59                       ` Christoph Lameter
2015-01-30 15:28                         ` Michal Hocko
2015-01-26 17:28           ` Michal Hocko
2015-01-26 18:35             ` Christoph Lameter
2015-01-26 22:11             ` Andrew Morton
2015-01-27 10:41               ` Michal Hocko
2015-01-27 10:33             ` Vinayak Menon [this message]
2015-01-27 10:45               ` Michal Hocko
2015-01-29 17:32       ` Christoph Lameter
2015-01-30 15:27         ` Michal Hocko
2015-01-16  1:17 ` Andrew Morton
2015-01-16  5:10   ` Vinayak Menon
2015-01-17 16:29   ` Vinayak Menon
2015-02-11 22:14     ` Andrew Morton
2015-02-12 16:19       ` Vlastimil Babka

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