From: Dave Chinner Subject: Re: page fault scalability (ext3, ext4, xfs) Date: Thu, 15 Aug 2013 14:29:30 +1000 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-Transfer-Encoding: 7bit Cc: Jan Kara , Dave Hansen , LKML , xfs@oss.sgi.com, Andy Lutomirski , linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, Tim Chen To: Andi Kleen Return-path: Content-Disposition: inline In-Reply-To: <20130815022401.GQ23412@tassilo.jf.intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com List-Id: linux-ext4.vger.kernel.org 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 _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs