From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262385AbULCV7O (ORCPT ); Fri, 3 Dec 2004 16:59:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262400AbULCV7O (ORCPT ); Fri, 3 Dec 2004 16:59:14 -0500 Received: from zcars04f.nortelnetworks.com ([47.129.242.57]:58578 "EHLO zcars04f.nortelnetworks.com") by vger.kernel.org with ESMTP id S262385AbULCV7K (ORCPT ); Fri, 3 Dec 2004 16:59:10 -0500 Message-ID: <41B0E18C.2060801@nortelnetworks.com> Date: Fri, 03 Dec 2004 15:58:36 -0600 X-Sybari-Space: 00000000 00000000 00000000 00000000 From: Chris Friesen User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040113 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Linux kernel , linuxppc-dev@ozlabs.org Subject: looking for help, attempting to debug high latency in 2.4 kernel Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi guys, I'm running 2.4.22 on ppc32. Embedded system, just 74xx cpu, dual tulip network links and fiberchannel card. Card has 1.5GB of memory, rootfs is tmpfs, system has some NFS mounts. We're seeing userspace delayed for almost a second every so often. No idea what's causing it. We've got scheduler instrumentation showing a usespace task starting to run, then a bunch of tasks being put on the runqueue, and finally we wake up and start running normally again almost a full second later. The timing is not exactly the same in each case, but it's usually close to a second of delay. I'm looking for some tips on how to go about tracking this down. Where are my delays likely to be coming from? Long-running code paths? Long periods with interrupts off? I dunno where to start. Would porting lockmeter be a good idea? Is there anyone who's already done this for ppc? I appreciate any help. Thanks, Chris