On Mon, 02 Jul 2012 11:43:48 +0200
Andreas Heinlein <aheinlein@xxxxxxx> wrote:
> Hello,
>
> we have a strange NFS problem with a newly setup Linux server, and I
> hope someone here can help.
>
> The symptom is that, slowly over time (speaking of several days up to 2
> weeks), the kernel nfsd processes/threads consume more and more CPU
> until the system finally becomes unresponsive. We recorded system
> activity with sar, which shows that CPU (system) usage slowly rises
> after reboot from about 1% to nearly 100% over the course of several
> days. Load averages stay around 0.1-0.3 until 100% are reached, up to
> this point the problem is almost not noticable from the clients. Then
> load averages climb up to 30.0; at this point the system becomes more or
> less unusable and has to be restarted. 'top' output shows the CPU usage
> evenly distributed across all nfsd threads.
>
> The system is a fairly recent, though entry level server with a Core i3
> and 4G RAM, hosting the home directories for about 15-20 clients. CPU
> activity does not drop at night, when no clients are connected. It is
> running Debian 6.0 with linux 3.2.0 (from the backports repository),
> with nfs-utils 1.2.5 (also from the backports repository). I suspect
> that these backports might be the culprit, but since we need this kernel
> for other purposes, and I cannot reboot that machine during office
> hours, I'd rather not try going back to the official Debian kernel
> without good reasons. If there are known problems, I'd give it a try.
>
Find the pid of one of the nfsd threads that's spinning, then get a
stack trace from it:
# cat /proc/<pidofnfsd>/stack
...that should give us some idea of what it's doing.
--
Jeff Layton <jlayton@xxxxxxxxxx>
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