On Wed, Oct 31, 2012 at 12:25:13PM +0100, Thorsten Leemhuis wrote:

On 30.10.2012 20:18, Mel Gorman wrote:

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On Mon, Oct 29, 2012 at 11:52:03AM +0100, Thorsten Leemhuis wrote:

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On 15.10.2012 13:09, Mel Gorman wrote:

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On Mon, Oct 15, 2012 at 11:54:13AM +0200, Jiri Slaby wrote:

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On 10/12/2012 03:57 PM, Mel Gorman wrote:

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mm: vmscan: scale number of pages reclaimed by reclaim/compaction only in direct reclaim
Jiri Slaby reported the following:

[...]

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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?

Excessive reclaim, high CPU usage by kswapd, processes getting stick in
isolate_migratepages or isolate_freepages.

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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) :-)

It wins at entertainment value if nothing else :)

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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 ;-)

No doubt it's the default private comment #1 !

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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.

Ok, great. Keep an eye on it please. If Jiri Slaby reports similar
success then I'll collapse the two patches together and resend to
Andrew.

Thanks.

-- 
Mel Gorman
SUSE Labs

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