From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ravikiran G Thirumalai Subject: Re: [patch 0/4] ide: Break ide_lock to per-hwgroup lock Date: Tue, 27 Sep 2005 08:20:26 -0700 Message-ID: <20050927152026.GC3822@localhost.localdomain> References: <20050906233322.GA3642@localhost.localdomain> <20050907091923.GE4785@suse.de> <20050907192747.GC3769@localhost.localdomain> <20050907193422.GS4785@suse.de> <58cb370e050927063674bb47a7@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from serv01.siteground.net ([70.85.91.68]:54938 "EHLO serv01.siteground.net") by vger.kernel.org with ESMTP id S964960AbVI0PUc (ORCPT ); Tue, 27 Sep 2005 11:20:32 -0400 Content-Disposition: inline In-Reply-To: <58cb370e050927063674bb47a7@mail.gmail.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Bartlomiej Zolnierkiewicz Cc: Jens Axboe , linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org, "Shai Fultheim (Shai@scalex86.org)" , Alok Kataria 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. 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. Thanks, Kiran