Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 9 Feb 2003 12:37:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 9 Feb 2003 12:37:22 -0500 Received: from mta02-svc.ntlworld.com ([62.253.162.42]:24541 "EHLO mta02-svc.ntlworld.com") by vger.kernel.org with ESMTP id ; Sun, 9 Feb 2003 12:37:20 -0500 From: Chris Rankin Message-Id: <200302091747.h19Hl30g031558@twopit.underworld> Subject: Re: Linux 2.4.20-SMP: where is all my CPU time going? To: hahn@physics.mcmaster.ca (Mark Hahn) Date: Sun, 9 Feb 2003 17:47:03 +0000 (GMT) Cc: linux-kernel@vger.kernel.org In-Reply-To: from "Mark Hahn" at Feb 09, 2003 12:23:26 PM X-Mailer: ELM [version 2.5 PL6] MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4259 Lines: 83 > > I have been running Linux-2.4.20-SMP on my dual PIII-9333MHz machine > > (1 GB RAM) for over 3 weeks as a desktop machine, with 2 instances of > > SETI@Home running at nice 19 in the background the whole time: > > but other unknown factors have changed, right? like daily use > of the desktop? Yes, I do *use* my destop occasionally... ;-). However, my full "SETI statistics" file contains daily data going back to October 2000. For example, here is a excerpt from September 2002: TIMESTAMP [2002] CLIENT NAME RUN-TIME SYS-TIME Sep 22 23:08:00: SETI-5 20606.560000 190.480000 Sep 23 02:19:22: SETI-1 31343.990000 289.770000 Sep 23 08:47:07: SETI-2 32592.250000 273.890000 Sep 23 11:19:43: SETI-3 30795.910000 265.160000 Sep 23 18:10:38: SETI-4 32877.130000 270.660000 Sep 23 20:11:08: SETI-6 30946.050000 265.570000 Sep 24 03:51:53: SETI-5 33192.640000 270.920000 Sep 24 05:53:52: SETI-1 33039.560000 279.380000 Sep 24 13:32:49: SETI-2 32785.650000 271.290000 Sep 24 15:38:35: SETI-3 33046.460000 282.480000 Sep 24 23:16:30: SETI-4 32947.420000 279.430000 Sep 25 00:12:22: SETI-6 28678.120000 259.580000 Sep 25 07:52:13: SETI-5 28920.640000 268.700000 Sep 25 10:57:25: SETI-1 33598.060000 554.140000 Sep 25 22:24:01: SETI-3 16284.640000 2286.710000 Sep 26 00:34:02: SETI-2 31303.880000 2678.700000 Sep 26 08:17:12: SETI-6 33268.100000 281.640000 Sep 26 09:52:11: SETI-5 31248.750000 276.190000 Sep 26 18:00:18: SETI-1 32560.010000 274.440000 Sep 26 19:08:24: SETI-3 31045.920000 269.040000 Sep 27 03:54:47: SETI-2 33266.910000 276.200000 Sep 27 04:46:27: SETI-4 32386.510000 272.180000 Sep 27 13:27:50: SETI-6 33058.870000 267.090000 Sep 27 14:21:14: SETI-5 33171.320000 271.520000 Sep 27 21:45:00: SETI-1 28743.730000 251.880000 Sep 27 23:59:34: SETI-3 33474.890000 261.430000 Sep 28 07:17:16: SETI-2 33210.900000 256.300000 I have not changed the way I have used this machine, and yet these "sys-spikes" only appear for two work units. This box should also not suffer from memory starvation: $ free -t total used free shared buffers cached Mem: 1033532 839516 194016 0 57468 596040 -/+ buffers/cache: 186008 847524 Swap: 498004 12000 486004 Total: 1531536 851516 680020 > > Feb 07 18:20:19: SETI-1 33722.820000 203.570000 > > Feb 09 06:14:08: SETI-1 33391.280000 2165.590000 > > do you have any other data? if the kernel happens to pull pages away > from the seti process, it could easily cause this sort of thing. Well, I actually have no idea what sort of activity counts towards the sys-time total. Is this time spent in spinlocks? Semaphores? Waiting for DMA transfers to complete? And we're talking 36 minutes-worth of sys-time here! It sounds as if some in-kernel process is going completely off the deep end. > check your cron jobs; I'm guessing you simply run updatedb or something > at that interval. it does enough IO to flush pages in the seti client's > working set. My only cron job is one that runs "rmmod -a" every hour. > that's just one possible perturber, though: there are plenty of other > mechanisms that would work fine to produce this kind of effect. > some sort of cache-thrashing in particular. Could cache-thrashing account for the 9 hours of missing run-time? I didn't see or hear any unusual disc activity last night, and the only processes in my run-queue were the two setiathome ones. Chris - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/