From: Jens Axboe Subject: Re: [patch,rfc v2] ext3/4: enhance fsync performance when using cfq Date: Thu, 8 Apr 2010 16:06:53 +0200 Message-ID: <20100408140653.GP10103@kernel.dk> References: <20100408110045.GJ10103@kernel.dk> <20100408135901.GA10879@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Vivek Goyal , Theodore Ts'o , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org To: Jeff Moyer Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Thu, Apr 08 2010, Jeff Moyer wrote: > Vivek Goyal writes: > > > On Thu, Apr 08, 2010 at 01:00:45PM +0200, Jens Axboe wrote: > > >> I like the concept, it's definitely useful (and your results amply > >> demonstrate that). I was thinking if there was a way in through the ioc > >> itself, rather than bdi -> queue and like you are doing. But I can't > >> think of a nice way to do it, so this is probably as good as it gets. > >> > > > > I think, one issue with ioc based approach will be that it will then call > > yield operation on all the devices in the system where this context has ever > > done any IO. With bdi based approach this call will remain limited to > > a smaller set of devices. > > Which actually brings up the question of whether this needs some > knowledge of whether the journal is on the same device as the file > system! In such a case, we need not yield. I think I'll stick my head > in the sand for this one. ;-) Yes, that is true. But that should be relatively easy to check. -- Jens Axboe