Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753941Ab1E3Upv (ORCPT ); Mon, 30 May 2011 16:45:51 -0400 Received: from ud10.udmedia.de ([194.117.254.50]:41536 "EHLO mail.ud10.udmedia.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751011Ab1E3Upu (ORCPT ); Mon, 30 May 2011 16:45:50 -0400 Date: Mon, 30 May 2011 22:45:48 +0200 From: Markus Trippelsdorf To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org Subject: Re: Very high CPU values in top on idle system (3.0-rc1) Message-ID: <20110530204548.GA1762@x4.trippels.de> References: <20110530173916.GA1746@x4.trippels.de> <1306778743.23844.5.camel@twins> <20110530182356.GA1762@x4.trippels.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110530182356.GA1762@x4.trippels.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2839 Lines: 65 On 2011.05.30 at 20:23 +0200, Markus Trippelsdorf wrote: > On 2011.05.30 at 20:05 +0200, Peter Zijlstra wrote: > > On Mon, 2011-05-30 at 19:39 +0200, Markus Trippelsdorf wrote: > > > I get very high CPU values when I run 'top' on my (mostly) idle system > > > with 3.0-rc1. For example mpd was always in the 1-2% range and is now > > > constantly over 50%. > > > > > > This is caused by: > > > > > > commit 317f394160e9beb97d19a84c39b7e5eb3d7815a8 > > > Author: Peter Zijlstra > > > Date: Tue Apr 5 17:23:58 2011 +0200 > > > > > > sched: Move the second half of ttwu() to the remote cpu > > > > > > When I revert the above I see sane CPU values again. > > > > So: echo NO_TTWU_QUEUE > /debug/sched_features, also cures it? > > Yes. > > > What architecture, what .config, and can you see it with anything other > > than mpd (yum search mpd, only seems to result in mpd clients not the > > actual server). > > Yes, mpd was just an example. _Every_ program that would normally show in > the 1-5% CPU range is now in the 30-70% range (X, xterm, etc.). IOW: % sudo echo TTWU_QUEUE >| /sys/kernel/debug/sched_features % top -b -n 1 top - 22:40:38 up 1:46, 11 users, load average: 0.00, 0.02, 0.05 Tasks: 109 total, 1 running, 108 sleeping, 0 stopped, 0 zombie Cpu(s): 1.0%us, 0.9%sy, 0.0%ni, 98.0%id, 0.1%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 8183132k total, 1365724k used, 6817408k free, 1632k buffers Swap: 2097148k total, 0k used, 2097148k free, 655208k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 881 mpd 20 0 122m 20m 4832 S 74 0.3 4:25.22 mpd 1564 root 20 0 99428 40m 4716 S 36 0.5 3:36.15 X 1648 markus 20 0 1147m 340m 39m S 16 4.3 1:17.90 firefox-bin 1649 markus 20 0 237m 33m 17m S 6 0.4 1:02.31 konsole % sudo echo NO_TTWU_QUEUE >| /sys/kernel/debug/sched_features % top -b -n 1 top - 22:42:07 up 1:48, 11 users, load average: 0.00, 0.01, 0.05 Tasks: 110 total, 1 running, 109 sleeping, 0 stopped, 0 zombie Cpu(s): 1.0%us, 0.9%sy, 0.0%ni, 98.0%id, 0.1%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 8183132k total, 1377308k used, 6805824k free, 1632k buffers Swap: 2097148k total, 0k used, 2097148k free, 659896k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1649 markus 20 0 237m 33m 17m S 2 0.4 1:17.69 konsole 1 root 20 0 160 28 12 S 0 0.0 0:16.95 minit 2 root 20 0 0 0 0 S 0 0.0 0:00.36 kthreadd -- Markus -- 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/