From: Ted Ts'o Subject: Re: Performance testing of various barrier reduction patches [was: Re: [RFC v4] ext4: Coordinate fsync requests] Date: Mon, 11 Oct 2010 10:33:17 -0400 Message-ID: <20101011143317.GA3860@thunk.org> References: <20100806070424.GD2109@tux1.beaverton.ibm.com> <20100809195324.GG2109@tux1.beaverton.ibm.com> <4D5AEB7F-32E2-481A-A6C8-7E7E0BD3CE98@dilger.ca> <20100809233805.GH2109@tux1.beaverton.ibm.com> <20100819021441.GM2109@tux1.beaverton.ibm.com> <20100823183119.GA28105@tux1.beaverton.ibm.com> <20100923232527.GB25624@tux1.beaverton.ibm.com> <20100927230111.GV25555@tux1.beaverton.ibm.com> <20101008212606.GE25624@tux1.beaverton.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Andreas Dilger , Mingming Cao , Ric Wheeler , linux-ext4 , linux-kernel , Keith Mannthey , Mingming Cao , Tejun Heo , hch@lst.de To: "Darrick J. Wong" Return-path: Received: from thunk.org ([69.25.196.29]:58018 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754622Ab0JKOdZ (ORCPT ); Mon, 11 Oct 2010 10:33:25 -0400 Content-Disposition: inline In-Reply-To: <20101008212606.GE25624@tux1.beaverton.ibm.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Fri, Oct 08, 2010 at 02:26:06PM -0700, Darrick J. Wong wrote: > Given the nearness of the merge window, perhaps we ought to discuss > this on Monday's ext4 call? In the meantime I'll clean up the fsync > coordination patch so that it doesn't have so many debugging knobs > and whistles. Yes, we should definitely talk about this on today's call. One of the things that concern me is that if I'm reading the spreadsheet correctly, there are some colums (for example, elm3c44_sas, comparing I3, which is what will be in 2.6.36 --- jan's patch, but not yours, and the currently existing behaviour --- with I10 which is as I understand it, what you are recommending, I see an FFSB regression from 1,916.54 to 1,690.33). That's something like a 15% regression. I know that for other hardware, there are improvements, but the fact that at least for some hardware we're seeing such a big regression makes me worried that we're missing something --- or maybe it's just me who is missing something about your spreadsheet? - Ted