Message-ID: <50910A99.5050707@leemhuis.info>
Date: Wed, 31 Oct 2012 12:25:13 +0100
From: Thorsten Leemhuis <fedora@leemhuis.info>
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To: Mel Gorman <mgorman@suse.de>
CC: Jiri Slaby <jslaby@suse.cz>, Valdis.Kletnieks@vt.edu,
        Jiri Slaby <jirislaby@gmail.com>, linux-mm@kvack.org,
        LKML <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: kswapd0: excessive CPU usage
References: <5076E700.2030909@suse.cz> <118079.1349978211@turing-police.cc.vt.edu> <50770905.5070904@suse.cz> <119175.1349979570@turing-police.cc.vt.edu> <5077434D.7080008@suse.cz> <50780F26.7070007@suse.cz> <20121012135726.GY29125@suse.de> <507BDD45.1070705@suse.cz> <20121015110937.GE29125@suse.de> <508E5FD3.1060105@leemhuis.info> <20121030191843.GH3888@suse.de>
In-Reply-To: <20121030191843.GH3888@suse.de>
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On 30.10.2012 20:18, Mel Gorman wrote:
> On Mon, Oct 29, 2012 at 11:52:03AM +0100, Thorsten Leemhuis wrote:
>> On 15.10.2012 13:09, Mel Gorman wrote:
>>> On Mon, Oct 15, 2012 at 11:54:13AM +0200, Jiri Slaby wrote:
>>>> On 10/12/2012 03:57 PM, Mel Gorman wrote:
>>>>> mm: vmscan: scale number of pages reclaimed by reclaim/compaction only in direct reclaim
>>>>> Jiri Slaby reported the following:
> [...]
>>>> Yes, applying this instead of the revert fixes the issue as well.
>> Just wondering, is there a reason why this patch wasn't applied to
>> mainline? Did it simply fall through the cracks? Or am I missing
>> something?
> It's because a problem was reported related to the patch (off-list,
> whoops). I'm waiting to hear if a second patch fixes the problem or not.

Anything in particular I should look out for while testing?

>> I'm asking because I think I stil see the issue on
>> 3.7-rc2-git-checkout-from-friday. Seems Fedora rawhide users are
>> hitting it, too:
>> https://bugzilla.redhat.com/show_bug.cgi?id=866988
> I like the steps to reproduce.

One of those cases where the bugzilla bug template was not very helpful 
or where it was not used as intended (you decide) :-)

> Is step 3 profit?

Yes, but psst, don't tell anyone; step 4 (world domination! for real!) 
is also hidden to keep that part of the big plan a secret for now ;-)

>> Or are we seeing something different which just looks similar?  I can
>> test the patch if it needs further testing, but from the discussion
>> I got the impression that everything is clear and the patch ready
>> for merging.
> It could be the same issue. Can you test with the "mm: vmscan: scale
> number of pages reclaimed by reclaim/compaction only in direct reclaim"
> patch and the following on top please?

Built a vanilla mainline kernel with those two patches and installed it 
on the machine where I was seeing problems high kswapd0 load on 3.7-rc3. 
Ran it an hour yesterday and a few hours today; seems the patches fix 
the issue for me as kswapd behaves:

$ LC_ALL=C ps -aux | grep 'kswapd'
root       62  0.0  0.0      0     0 ?      S    Oct30   0:05 [kswapd0]

So everything is looking fine again so far thx to the two patches  -- 
hopefully it stays that way even after hitting "send" in my mailer in a 
few seconds.

CU
knurd
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