Date: Wed, 23 Nov 2005 12:35:31 -0800
From: Andrew Morton <akpm@osdl.org>
To: Jan Kasprzak <kas@fi.muni.cz>
Cc: nickpiggin@yahoo.com.au, linux-kernel@vger.kernel.org
Subject: Re: 2.6.14 kswapd eating too much CPU
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Jan Kasprzak <kas@fi.muni.cz> wrote:
>
> Andrew Morton wrote:
> : Jan Kasprzak <kas@fi.muni.cz> wrote:
> : >
> : > 	I am at 2.6.15-rc2 now, the problem is still there.
> : >  Currently according to top(1), kswapd1 eats >98% CPU for 50 minutes now
> : >  and counting.
> : 
> : When it's doing this, could you do sysrq-p a few times?  The output of that
> : should tell us where the CPU is executing.
> 
> 	Hmm, it does not show anything but the header. Should I enable
> something special in the kernel?

Try `dmesg -n 7' first.

> # dmesg -c >/dev/null; echo -n p >/proc/sysrq-trigger ; sleep 5; dmesg
> SysRq : Show Regs
> # 

You won't get anything useful from sysrq-p via /proc/sysrq-trigger - it'll
just show the backtrace of the process `echo'.  It has to be via the
keyboard.

If there's no keyboard, do `echo t > /proc/sysrq-trigger' to get an
all-task backtrace, then locate the trace for kswapd in the resulting
output.

Thanks.

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