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From: "Jindřich Makovička" <makovick@gmail.com>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: linux-kernel@vger.kernel.org, Mel Gorman <mel@csn.ul.ie>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: khugepaged: gets stuck when writing to USB flash, 2.6.38-rc2
Date: Tue, 1 Feb 2011 22:24:00 +0100	[thread overview]
Message-ID: <AANLkTi=bqnaif=7xdLFDny86-WYJONRZB45Q=ekKMMst@mail.gmail.com> (raw)
In-Reply-To: <20110201154947.GX16981@random.random>

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2011/2/1 Andrea Arcangeli <aarcange@redhat.com>:
>> When copying 4GB or more in one go from HDD to Flash, during the
>> copying, fork() and probably other syscalls involving VM start
>> blocking (I first observed the problem in Chrome, which refused to
>> display content in new tabs). When one lets the copying finish, the
>> system returns to a usable state.
>>
>> During the limbo, khugepaged is in D state (uninterruptible sleep).
>
> That means no hugepage could be allocated. Maybe memory compaction is
> doing an overwork because all pagecache is dirty and can't be
> migrated. This should solve it if it's memory compaction:
>
> echo never >/sys/kernel/mm/transparent_hugepage/defrag
>
> kswapd state would be interesting too. Can you sysrq+t?

With -rc2, there is

$ ps aux | grep -E "kswap|khugep"
root       474  0.0  0.0      0     0 ?        S    20:44   0:00 [kswapd0]
root       540  0.0  0.0      0     0 ?        DN   20:44   0:00 [khugepaged]

Sysrq-t output is attached.

Good news is, I don't see these issues with -rc3.

Regards,
-- 
Jindrich Makovicka

[-- Attachment #2: sysrq-t.txt.gz --]
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  reply	other threads:[~2011-02-01 21:24 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-01-31 19:28 Jindřich Makovička
2011-02-01 15:49 ` Andrea Arcangeli
2011-02-01 21:24   ` Jindřich Makovička [this message]
2011-02-02  0:26     ` Andrea Arcangeli
2011-02-03 13:24   ` Mel Gorman
2011-02-03 19:06     ` Andrea Arcangeli
2011-02-03 21:16       ` Jindřich Makovička
2011-02-04 15:48         ` Andrea Arcangeli
2011-02-13 10:47           ` Jindřich Makovička

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