Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932214AbWEWWWr (ORCPT ); Tue, 23 May 2006 18:22:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932461AbWEWWWr (ORCPT ); Tue, 23 May 2006 18:22:47 -0400 Received: from omx2-ext.sgi.com ([192.48.171.19]:48595 "EHLO omx2.sgi.com") by vger.kernel.org with ESMTP id S932214AbWEWWWq (ORCPT ); Tue, 23 May 2006 18:22:46 -0400 Date: Wed, 24 May 2006 08:22:19 +1000 From: Nathan Scott To: Jan Engelhardt Cc: xfs@oss.sgi.com, linux-kernel@vger.kernel.org Subject: Re: XFS write speed drop Message-ID: <20060524082218.A267844@wobbly.melbourne.sgi.com> References: <20060522105326.A212600@wobbly.melbourne.sgi.com> <20060523084309.A239136@wobbly.melbourne.sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: ; from jengelh@linux01.gwdg.de on Tue, May 23, 2006 at 03:23:31PM +0200 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1328 Lines: 31 On Tue, May 23, 2006 at 03:23:31PM +0200, Jan Engelhardt wrote: > >> CASE 1: Copying from one disk to another > >> ======================================== > >> Copying a compiled 2.6.17-rc4 tree; 306907 KB in 28566 files in 2090 > >> directories. > > > >OK, we can call this a metadata intensive workload - lots of small > >files, lots of creates. Barriers will hurt the most here, as we'd > >already have been log I/O bound most likely, and I'd expect barriers > >to only slow that further. > > > Yes and the most important thing is that someone made -o barrier the > default and did not notice. Someone else? :-D Not sure what you're trying to say here. Yes, barriers are on by default now if the hardware supports them, yes, they will slow things down relative to write-cache-without-barriers, and yes we all knew that ... its not the case that someone "did not notice" or forgot about something. There is no doubt that this is the right thing to be doing by default - there's no way that I can tell from inside XFS in the kernel that you have a UPS. ;) cheers. -- Nathan - 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/