From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bartlomiej Zolnierkiewicz Subject: Re: [patch 0/4] ide: Break ide_lock to per-hwgroup lock Date: Tue, 27 Sep 2005 15:36:40 +0200 Message-ID: <58cb370e050927063674bb47a7@mail.gmail.com> References: <20050906233322.GA3642@localhost.localdomain> <20050907091923.GE4785@suse.de> <20050907192747.GC3769@localhost.localdomain> <20050907193422.GS4785@suse.de> Reply-To: Bartlomiej Zolnierkiewicz Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Return-path: In-Reply-To: <20050907193422.GS4785@suse.de> Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org To: Jens Axboe Cc: Ravikiran G Thirumalai , linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org, "Shai Fultheim (Shai@scalex86.org)" , Alok Kataria List-Id: linux-ide@vger.kernel.org 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? > > > > > > > On smp machines with multiple ide interfaces, we take per-group lock instead > > of a global lock, there by breaking the lock to per-irq hwgroups. > > I realize the theory behind breaking up locks, I'm just wondering about > this specific case. Please show actual contention data promoting this > specific case, we don't break up locks "just because". > > 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? Bartlomiej