From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: linux-nfs-owner@vger.kernel.org Received: from mailout-de.gmx.net ([213.165.64.22]:57609 "HELO mailout-de.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754482Ab2GBJnv (ORCPT ); Mon, 2 Jul 2012 05:43:51 -0400 Message-ID: <4FF16D54.6090200@gmx.com> Date: Mon, 02 Jul 2012 11:43:48 +0200 From: Andreas Heinlein MIME-Version: 1.0 To: linux-nfs@vger.kernel.org Subject: Kernel NFSd CPU hog? Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: linux-nfs-owner@vger.kernel.org List-ID: 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. Can anyone help me? Thanks, Andreas