From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756891AbYICXB4 (ORCPT ); Wed, 3 Sep 2008 19:01:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753548AbYICXBN (ORCPT ); Wed, 3 Sep 2008 19:01:13 -0400 Received: from smtp.ono.com ([62.42.230.12]:51665 "EHLO resmaa02.ono.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753543AbYICXBL convert rfc822-to-8bit (ORCPT ); Wed, 3 Sep 2008 19:01:11 -0400 Date: Thu, 4 Sep 2008 01:00:43 +0200 From: "J.A. =?UTF-8?B?TWFnYWxsw7Nu?=" To: Linux-Kernel Subject: Re: Finding what is stuck... Message-ID: <20080904010043.408b3f03@one.home> In-Reply-To: <20080901170812.2c3b041b@infradead.org> References: <20080902020447.5b48b083@one.home> <20080901170812.2c3b041b@infradead.org> X-Mailer: Claws Mail 3.5.0 (GTK+ 2.13.7; i586-mandriva-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 1 Sep 2008 17:08:12 -0700, Arjan van de Ven wrote: > On Tue, 2 Sep 2008 02:04:47 +0200 > "J.A. Magallón" wrote: > > > Hi all... > > > > I'm running 2.6.27-rc5-git2 on an Aspire One. > > The system is in general pretty responsive, but sometimes it just gets > > totally stuck. Even the mouse stops. > > > > It looks related to disk (SSD) access, but I'm not totally sure. > > Is there any way to find what is getting stuck ? I know that SSDs can > > be slow on write, I don't mind if the system is faster or slower > > (it's small :))), but if the speed is constant. That occasional > > pauses are strange, like if SSD flushing gets stuck on BKL > > (I know, no idea about what I talk...). > > > > I'm using ext3 fs, noop iosched. But as I say, I'm not sure that the > > disk writes are the culprit. > > > > Any idea about how to find this ? > > Have you tried to run "latencytop"? > (you need to enable this in the kernel config as well) > > it tends to (for me at least) point out very well where stalls happen, > or at least, what the system is doing when they happen. > > (hint: make sure you do "make install" before running it) > These are some shots of latencytop while working. I copied the screen when I saw any very high timing... Cause Maximum Percentage Walking directory tree 790.2 msec 10.6 % Scheduler: waiting for cpu 40.5 msec 38.5 % fsync() on a file 3191.6 msec 36.7 % Reading EXT3 directory 1553.3 msec 3.9 % EXT3: Waiting for journal access 1518.7 msec 3.8 % Deleting an inode 657.5 msec 1.7 % EXT3: Looking for file 576.3 msec 1.4 % Writing a page to disk 363.0 msec 6.1 % call_usermodehelper_exec request_module __sock_cre 69.4 msec 0.2 % Scheduler: waiting for cpull 28.0 msec 18.9 % Page fault 7.9 msec 0.3 % fsync() on a file 8843.7 msec 81.8 % Writing a page to disk 1548.6 msec 2.9 % EXT3: Waiting for journal access 356.5 msec 1.1 % Scheduler: waiting for cpu 40.6 msec 6.0 % EXT3: Waiting for journal access 6153.6 msec 17.2 % fsync() on a file 4902.7 msec 53.5 % Writing a page to disk 3487.2 msec 9.8 % Writing buffer to disk (synchronous) 2288.7 msec 4.6 % synchronous write 1320.6 msec 2.6 % Truncating file 302.6 msec 0.6 % Page fault 290.5 msec 0.6 % Scheduler: waiting for cpu 13.4 msec 4.5 % Waiting for event (select) 5.0 msec 5.0 % Deleting an inode 5584.7 msec 27.5 % Writing a page to disk 829.2 msec 5.4 % fsync() on a file 265.1 msec 11.2 % Scheduler: waiting for cpu 37.2 msec 11.5 % stat() operation 5.6 msec 0.1 % Page fault 5.5 msec 0.2 % Waiting for event (select) 5.0 msec 39.8 % Waiting for event (poll) 5.0 msec 2.5 % synchronous write 4.2 msec 0.0 % All look fs access: one:~# df Filesystem Type Size Used Avail Use% Mounted on /dev/sda1 ext3 6.9G 3.7G 3.2G 55% / tmpfs tmpfs 246M 12K 246M 1% /tmp /dev/mmcblk0p1 ext3 1.9G 35M 1.8G 2% /store I will try mounting root as ext2, to rule out jorunaling... TIA -- J.A. Magallon \ Software is like sex: \ It's better when it's free Mandriva Linux release 2008.1 (Cooker) for i586 Linux kernel 2.6.23-jam01, gcc version 4.2.2 20070909