From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 6 Sep 2007 02:50:10 -0700 (PDT) From: Martin Knoblauch Reply-To: spamtrap@knobisoft.de Subject: Re: huge improvement with per-device dirty throttling In-Reply-To: <713371.64716.qm@web32603.mail.mud.yahoo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Message-ID: <351207.28447.qm@web32602.mail.mud.yahoo.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Leroy van Logchem , linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Peter zijlstra List-ID: --- Martin Knoblauch wrote: > > --- Leroy van Logchem wrote: > > > Andrea Arcangeli wrote: > > > On Wed, Aug 22, 2007 at 01:05:13PM +0200, Andi Kleen wrote: > > >> Ok perhaps the new adaptive dirty limits helps your single disk > > >> a lot too. But your improvements seem to be more "collateral > > damage" @) > > >> > > >> But if that was true it might be enough to just change the dirty > > limits > > >> to get the same effect on your system. You might want to play > with > > >> /proc/sys/vm/dirty_* > > > > > > The adaptive dirty limit is per task so it can't be reproduced > with > > > global sysctl. It made quite some difference when I researched > into > > it > > > in function of time. This isn't in function of time but it > > certainly > > > makes a lot of difference too, actually it's the most important > > part > > > of the patchset for most people, the rest is for the corner cases > > that > > > aren't handled right currently (writing to a slow device with > > > writeback cache has always been hanging the whole thing). > > > > > > Self-tuning > static sysctl's. The last years we needed to use very > > > small values for dirty_ratio and dirty_background_ratio to soften > the > > > > latency problems we have during sustained writes. Imo these patches > > > really help in many cases, please commit to mainline. > > > > -- > > Leroy > > > > while it helps in some situations, I did some tests today with > 2.6.22.6+bdi-v9 (Peter was so kind) which seem to indicate that it > hurts NFS writes. Anyone seen similar effects? > > Otherwise I would just second your request. It definitely helps the > problematic performance of my CCISS based RAID5 volume. > please disregard my comment about NFS write performance. What I have seen is caused by some other stuff I am toying with. So, I second your request to push this forward. Martin ------------------------------------------------------ Martin Knoblauch email: k n o b i AT knobisoft DOT de www: http://www.knobisoft.de -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org