Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752216Ab3HOE37 (ORCPT ); Thu, 15 Aug 2013 00:29:59 -0400 Received: from ipmail05.adl6.internode.on.net ([150.101.137.143]:36748 "EHLO ipmail05.adl6.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751121Ab3HOE35 (ORCPT ); Thu, 15 Aug 2013 00:29:57 -0400 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AnoFAOFYDFJ5LCJRgWdsb2JhbABavVKFWoEgFw4BARYmKIIkAQECAgE6HCMFCwgDDgoJJQ8FJQMhE4gKBbluFpA6B4QSA5djlQAq Date: Thu, 15 Aug 2013 14:29:30 +1000 From: Dave Chinner To: Andi Kleen Cc: Dave Hansen , linux-fsdevel@vger.kernel.org, xfs@oss.sgi.com, linux-ext4@vger.kernel.org, Jan Kara , LKML , Tim Chen , Andy Lutomirski Subject: Re: page fault scalability (ext3, ext4, xfs) Message-ID: <20130815042930.GO6023@dastard> References: <520BB9EF.5020308@linux.intel.com> <20130815002436.GI6023@dastard> <20130815022401.GQ23412@tassilo.jf.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130815022401.GQ23412@tassilo.jf.intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1201 Lines: 31 On Wed, Aug 14, 2013 at 07:24:01PM -0700, Andi Kleen wrote: > > And FWIW, it's no secret that XFS has more per-operation overhead > > than ext4 through the write path when it comes to allocation, so > > it's no surprise that on a workload that is highly dependent on > > allocation overhead that ext4 is a bit faster.... > > This cannot explain a worse scaling curve though? The scaling curve is pretty much identical. The difference in performance will be the overhead of timestamp updates through the transaction subsystems of the filesystems. > w-i-s is all about scaling. Sure, but scaling *what*? It's spending all it's time in the filesystem through the .page_mkwrite path. It's not a page fault scaling test - it's a filesystem overwrite test that uses mmap. Indeed, I bet if you replace the mmap() with a write(fd, buf, 4096) loop, you'd get almost identical behaviour from the filesystems. Cheers, Dave. -- Dave Chinner david@fromorbit.com -- 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/