Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964972AbVI0P0V (ORCPT ); Tue, 27 Sep 2005 11:26:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964975AbVI0P0V (ORCPT ); Tue, 27 Sep 2005 11:26:21 -0400 Received: from ns.virtualhost.dk ([195.184.98.160]:53539 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S964972AbVI0P0U (ORCPT ); Tue, 27 Sep 2005 11:26:20 -0400 Date: Tue, 27 Sep 2005 17:26:42 +0200 From: Jens Axboe To: Ravikiran G Thirumalai Cc: Bartlomiej Zolnierkiewicz , linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org, "Shai Fultheim (Shai@scalex86.org)" , Alok Kataria Subject: Re: [patch 0/4] ide: Break ide_lock to per-hwgroup lock Message-ID: <20050927152641.GF2811@suse.de> References: <20050906233322.GA3642@localhost.localdomain> <20050907091923.GE4785@suse.de> <20050907192747.GC3769@localhost.localdomain> <20050907193422.GS4785@suse.de> <58cb370e050927063674bb47a7@mail.gmail.com> <20050927152026.GC3822@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050927152026.GC3822@localhost.localdomain> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2222 Lines: 51 On Tue, Sep 27 2005, Ravikiran G Thirumalai wrote: > On Tue, Sep 27, 2005 at 03:36:40PM +0200, Bartlomiej Zolnierkiewicz wrote: > > On 9/7/05, Jens Axboe wrote: > > > On Wed, Sep 07 2005, Ravikiran G Thirumalai wrote: > > > > On Wed, Sep 07, 2005 at 11:19:24AM +0200, Jens Axboe wrote: > > > > > On Tue, Sep 06 2005, Ravikiran G Thirumalai wrote: > > > > > > The following patchset breaks down the global ide_lock to per-hwgroup lock. > > > > > > We have taken the following approach. > > > > > > > > > > Curious, what is the point of this? > > > > > > > > > > > > > > > I'm asking because I've never heard anyone complain about IDE lock > > > contention and a proper patch usually comes with analysis of why it is > > > needed. > > > > Since ide_lock spinlock is used for all drives as queue lock and for all > > controllers as IDE lock I guess that with multiple controllers there is a lot > > contention on it... > > > > Breaking ide_lock is fine with me however seeing numbers would > > greatly help in getting wider acceptance for this change, Ravikiran? > > > > With the lock breakdown, Iozone read performance went up by 5.5% on a 2 way > x86 xeon box, with two hwifs and two processes reading from disks connected > to each hwif. There seems to be a small regression on Iozone write > tests -- about 1.5%. Maybe this is measurement noise as there is no apparent > reason for this. We plan to run more tests to see if the regression for > writes is statistically significant. You should run it eg 10 times on each kernel to get a feel for the variance of the results. Were you testing 2 or 4 disks? Some profile information for both kernels would also be paramount. > Btw, there was some problem with the moving of tuning code in this patchset > causing disks not to work in DMA mode. We were fixing that; will publish a > newer patchset with test results soon. I take it the numbers posted were for DMA enabled on all disks? -- Jens Axboe - 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/