2004-10-24 18:29:35

by Joerg Sommrey

[permalink] [raw]
Subject: Bug? Load avg 2.0 when idle.

Hello,

there is a load average of 2.0+ even if the box is almost idle. (i.e. "top"
shows just one running process: top itself.) Starting two cpu-intensive
processes raises the load average to 4.0+. How can I determine the
source for the high load, or is this a bug?
I'm running 2.6.9 on a dual-athlon box.

Thanks,
-jo

--
-rw-r--r-- 1 jo users 63 2004-10-24 19:38 /home/jo/.signature


2004-10-24 18:44:05

by Jan Knutar

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Subject: Re: Bug? Load avg 2.0 when idle.

On Sunday 24 October 2004 21:29, Joerg Sommrey wrote:
> Hello,
>
> there is a load average of 2.0+ even if the box is almost idle. (i.e. "top"
> shows just one running process: top itself.) Starting two cpu-intensive
> processes raises the load average to 4.0+. How can I determine the
> source for the high load, or is this a bug?
> I'm running 2.6.9 on a dual-athlon box.

Look for processes stuck in D state...

2004-10-24 18:45:31

by Christian Borntraeger

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Subject: Re: Bug? Load avg 2.0 when idle.

Joerg Sommrey wrote:
> there is a load average of 2.0+ even if the box is almost idle. (i.e.
> "top" shows just one running process: top itself.) Starting two
> cpu-intensive processes raises the load average to 4.0+. How can I
> determine the source for the high load, or is this a bug?
> I'm running 2.6.9 on a dual-athlon box.

Besides other possibilities, a bug in the kernel could be the cause.
Please check if any process (one or two) is in uninterruptible sleep.
(using ps axl the state is D)
Furthermore, Magic SysRequest+T (alt-print-t) and the dmesg output could
give some hints.
If there is nothing suspicious you might try some profiling tool, e.g.
OProfile.

There was another bug report about a wrap around load average. I dont know
if both reports are related.

cheers

Christian

2004-10-24 18:54:16

by Jan Engelhardt

[permalink] [raw]
Subject: Re: Bug? Load avg 2.0 when idle.

>> there is a load average of 2.0+ even if the box is almost idle. (i.e.
>> "top" shows just one running process: top itself.) Starting two
>> cpu-intensive processes raises the load average to 4.0+. How can I
>> determine the source for the high load, or is this a bug?
>> I'm running 2.6.9 on a dual-athlon box.
>
>Besides other possibilities, a bug in the kernel could be the cause.
>Please check if any process (one or two) is in uninterruptible sleep.
>(using ps axl the state is D)
>Furthermore, Magic SysRequest+T (alt-print-t) and the dmesg output could
>give some hints.
>If there is nothing suspicious you might try some profiling tool, e.g.
>OProfile.
>
>There was another bug report about a wrap around load average. I dont know
>if both reports are related.

My ?2: Start the kernel with init=/bin/sash (or some other minimalistic shell),
if the load average is "normal" (i.e. 0.0), then it's probably somewhere in
userspace.



Jan Engelhardt
--
Gesellschaft f?r Wissenschaftliche Datenverarbeitung
Am Fassberg, 37077 G?ttingen, http://www.gwdg.de

2004-10-24 18:59:20

by Joerg Sommrey

[permalink] [raw]
Subject: Re: Bug? Load avg 2.0 when idle.

On Sun, Oct 24, 2004 at 08:45:04PM +0200, Christian Borntraeger wrote:
> Joerg Sommrey wrote:
> > there is a load average of 2.0+ even if the box is almost idle. (i.e.
> > "top" shows just one running process: top itself.) Starting two
> > cpu-intensive processes raises the load average to 4.0+. How can I
> > determine the source for the high load, or is this a bug?
> > I'm running 2.6.9 on a dual-athlon box.
>
> Besides other possibilities, a bug in the kernel could be the cause.
> Please check if any process (one or two) is in uninterruptible sleep.
> (using ps axl the state is D)

On Sun, Oct 24, 2004 at 09:43:42PM +0300, Jan Knutar wrote:
>
> Look for processes stuck in D state...

Thanks,
there was something hanging in D state. Strange enough: it was waiting
for modules to be loaded. After killing a hanging "modprobe" (S state),
the D state processes vanished and load avg returned to normal values.

-jo

--
-rw-r--r-- 1 jo users 63 2004-10-24 19:38 /home/jo/.signature