From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Ts'o Subject: Re: page fault scalability (ext3, ext4, xfs) Date: Wed, 14 Aug 2013 15:43:59 -0400 Message-ID: <20130814194359.GA22316@thunk.org> References: <520BB9EF.5020308@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Andi Kleen , Jan Kara , LKML , xfs@oss.sgi.com, Andy Lutomirski , linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, Tim Chen To: Dave Hansen Return-path: Content-Disposition: inline In-Reply-To: <520BB9EF.5020308@linux.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 Thanks dave for doing this comparison. Is there any chance you can check whether lockstats shows anything interesting? > Test case is this: > > https://github.com/antonblanchard/will-it-scale/blob/master/tests/page_fault3.c One interesting thing about the test case. It looks like the first time through the while loop, the file will need to be extended (since it is a new tempfile). But subsequent times through the list the blocks for the file will already be allocated. If the file is prezero'ed ahead of time, so we're only measuring the cost of the write page fault, and we take block allocation out of the comparison, do we see the same scalability curve? Thanks, - Ted _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760404Ab3HNToT (ORCPT ); Wed, 14 Aug 2013 15:44:19 -0400 Received: from imap.thunk.org ([74.207.234.97]:43698 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760381Ab3HNToO (ORCPT ); Wed, 14 Aug 2013 15:44:14 -0400 Date: Wed, 14 Aug 2013 15:43:59 -0400 From: "Theodore Ts'o" To: Dave Hansen Cc: linux-fsdevel@vger.kernel.org, xfs@oss.sgi.com, linux-ext4@vger.kernel.org, Jan Kara , LKML , david@fromorbit.com, Tim Chen , Andi Kleen , Andy Lutomirski Subject: Re: page fault scalability (ext3, ext4, xfs) Message-ID: <20130814194359.GA22316@thunk.org> Mail-Followup-To: Theodore Ts'o , Dave Hansen , linux-fsdevel@vger.kernel.org, xfs@oss.sgi.com, linux-ext4@vger.kernel.org, Jan Kara , LKML , david@fromorbit.com, Tim Chen , Andi Kleen , Andy Lutomirski References: <520BB9EF.5020308@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <520BB9EF.5020308@linux.intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: tytso@thunk.org X-SA-Exim-Scanned: No (on imap.thunk.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Thanks dave for doing this comparison. Is there any chance you can check whether lockstats shows anything interesting? > Test case is this: > > https://github.com/antonblanchard/will-it-scale/blob/master/tests/page_fault3.c One interesting thing about the test case. It looks like the first time through the while loop, the file will need to be extended (since it is a new tempfile). But subsequent times through the list the blocks for the file will already be allocated. If the file is prezero'ed ahead of time, so we're only measuring the cost of the write page fault, and we take block allocation out of the comparison, do we see the same scalability curve? Thanks, - Ted