From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [PATCH 3/8] writeback: switch to per-bdi threads for flushing data Date: Tue, 8 Sep 2009 16:21:18 +0200 Message-ID: <20090908142118.GZ18599@kernel.dk> References: <1252401791-22463-1-git-send-email-jens.axboe@oracle.com> <1252401791-22463-4-git-send-email-jens.axboe@oracle.com> <1252417606.14793.3.camel@desktop> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, chris.mason@oracle.com, david@fromorbit.com, hch@infradead.org, akpm@linux-foundation.org, jack@suse.cz To: Daniel Walker Return-path: Received: from brick.kernel.dk ([93.163.65.50]:58056 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750897AbZIHOVQ (ORCPT ); Tue, 8 Sep 2009 10:21:16 -0400 Content-Disposition: inline In-Reply-To: <1252417606.14793.3.camel@desktop> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Tue, Sep 08 2009, Daniel Walker wrote: > On Tue, 2009-09-08 at 11:23 +0200, Jens Axboe wrote: > > This gets rid of pdflush for bdi writeout and kupdated style cleaning. > > pdflush writeout suffers from lack of locality and also requires more > > threads to handle the same workload, since it has to work in a > > non-blocking fashion against each queue. This also introduces lumpy > > behaviour and potential request starvation, since pdflush can be starved > > for queue access if others are accessing it. A sample ffsb workload that > > does random writes to files is about 8% faster here on a simple SATA drive > > during the benchmark phase. File layout also seems a LOT more smooth in > > vmstat: > > > This patch has a checkpatch error, and couple of warnings.. Here's one > of the warnings which I though was concerning.. > > WARNING: trailing semicolon indicates no statements, indent implies > otherwise > #388: FILE: fs/fs-writeback.c:177: > + } else if (wb->task); > + wake_up_process(wb->task); > > I suppose that could be a defect .. btw, patch 7 of 8 also has a few > trivial warnings. Oops yes, that was added between -v18 and -19 with the moving of that code. Will fix that up, thanks for spotting that. I'll check the series for checkpatch cleanliness. I did at some point, but that was a few revisions ago. -- Jens Axboe