From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753266AbYIQILg (ORCPT ); Wed, 17 Sep 2008 04:11:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751296AbYIQILV (ORCPT ); Wed, 17 Sep 2008 04:11:21 -0400 Received: from web32603.mail.mud.yahoo.com ([68.142.207.230]:24154 "HELO web32603.mail.mud.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751432AbYIQILT (ORCPT ); Wed, 17 Sep 2008 04:11:19 -0400 X-YMail-OSG: Q8de91AVM1kKdw.YIq2T.ZzQEUbCF_VIipsgFj.l_0cRZd0M7XsHXhMvl4yE9Ox1aQk8sA2p8xTJnNEXlXVMw41KxJ8xgeFdD404TKY1w6iEt3_q30p6SgE.VE0uaKw- X-RocketYMMF: knobi.rm X-Mailer: YahooMailRC/1096.28 YahooMailWebService/0.7.218.2 Date: Wed, 17 Sep 2008 01:11:17 -0700 (PDT) From: Martin Knoblauch Subject: Re: How to find out, what "pdflush" is working on To: Chris Snook Cc: linux-kernel@vger.kernel.org, Peter zijlstra , Fengguang Wu MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Message-ID: <33099.10057.qm@web32603.mail.mud.yahoo.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ----- Original Message ---- > From: Chris Snook > To: Martin Knoblauch > Cc: linux-kernel@vger.kernel.org; Peter zijlstra ; Fengguang Wu > Sent: Tuesday, September 16, 2008 9:07:29 PM > Subject: Re: How to find out, what "pdflush" is working on > > Martin Knoblauch wrote: > > Hi, > > > > I find the following comment in mm/pdflush.c > > > > /* * The pdflush threads are worker threads for writing back dirty data. * > > Ideally, we'd like one thread per active disk spindle. But the disk * > > topology is very hard to divine at this level. Instead, we take * care in > > various places to prevent more than one pdflush thread from * performing > > writeback against a single filesystem. pdflush threads * have the PF_FLUSHER > > flag set in current->flags to aid in this. */ > > > > Is there a way to find out what a certain instance of "pdflush" is working > > on? Like which block-device or which fliesystem it is writing to? I am still > > (2.6.27) trying to track down why writing a single file can make linux very > > sluggish and unresponsive. If that happens I usually see all possible 8 > > "pdflush" threads being in "D"-state. According to above comment only one of > > them should be really busy. > > The key word is "ideally". We'd like it to work that way, but it doesn't. > Patches to fix this are welcome. > Now, I am pretty much aware that apparently things are not "ideal". Therefore my question. Because before doing patches, one has to analyze. Cheers Martin