From mboxrd@z Thu Jan 1 00:00:00 1970 From: Frederic Weisbecker Subject: Re: [PATCH 0/11] Per-bdi writeback flusher threads v9 Date: Sat, 6 Jun 2009 03:00:34 +0200 Message-ID: <20090606010033.GB7809@nowhere> References: <1243511204-2328-1-git-send-email-jens.axboe@oracle.com> <20090604152040.GA6007@nowhere> <20090604120726.708a2211.akpm@linux-foundation.org> <20090604191309.GA4862@nowhere> <20090604195013.GB11363@kernel.dk> <20090604201012.GD11363@kernel.dk> <20090604223449.GA13780@nowhere> <20090605191528.GV11363@kernel.dk> <20090605211438.GA11650@duck.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jens Axboe , Andrew Morton , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, tytso@mit.edu, chris.mason@oracle.com, david@fromorbit.com, hch@infradead.org, yanmin_zhang@linux.intel.com, richard@rsk.demon.co.uk, damien.wyart@free.fr To: Jan Kara Return-path: Content-Disposition: inline In-Reply-To: <20090605211438.GA11650@duck.suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Fri, Jun 05, 2009 at 11:14:38PM +0200, Jan Kara wrote: > On Fri 05-06-09 21:15:28, Jens Axboe wrote: > > On Fri, Jun 05 2009, Frederic Weisbecker wrote: > > > The result with noop is even more impressive. > > > > > > See: http://kernel.org/pub/linux/kernel/people/frederic/dbench-noop.pdf > > > > > > Also a comparison, noop with pdflush against noop with bdi writeback: > > > > > > http://kernel.org/pub/linux/kernel/people/frederic/dbench-noop-cmp.pdf > > > > OK, so things aren't exactly peachy here to begin with. It may not > > actually BE an issue, or at least now a new one, but that doesn't mean > > that we should not attempt to quantify the impact. > What looks interesting is also the overall throughput. With pdflush we > get to 2.5 MB/s + 26 MB/s while with per-bdi we get to 2.7 MB/s + 13 MB/s. > So per-bdi seems to be *more* fair but throughput suffers a lot (which > might be inevitable due to incurred seeks). Heh indeed, I was confused with the colors here but yes pdflush has a faster total and a higher unfairness with noop, at least with this test. > Frederic, how much does dbench achieve for you just on one partition > (test both consecutively if possible) with as many threads as have those > two dbench instances together? Thanks. Good idea, I'll try it out so that there wouldn't have any per superblock ordering there, or whathever that could be. Thanks. > Honza > -- > Jan Kara > SUSE Labs, CR