Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757233AbZFZJQE (ORCPT ); Fri, 26 Jun 2009 05:16:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753660AbZFZJPz (ORCPT ); Fri, 26 Jun 2009 05:15:55 -0400 Received: from lon1-post-2.mail.demon.net ([195.173.77.149]:51121 "EHLO lon1-post-2.mail.demon.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753135AbZFZJPy (ORCPT ); Fri, 26 Jun 2009 05:15:54 -0400 Subject: Re: [RFC][PATCH] mm: stop balance_dirty_pages doing too much work From: Richard Kennedy To: Jens Axboe Cc: Peter Zijlstra , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org In-Reply-To: <20090625091033.GF31415@kernel.dk> References: <1245839904.3210.85.camel@localhost.localdomain> <20090624152732.d6352f4f.akpm@linux-foundation.org> <1245916833.31755.78.camel@twins> <20090625091033.GF31415@kernel.dk> Content-Type: text/plain Date: Fri, 26 Jun 2009 10:15:55 +0100 Message-Id: <1246007755.2692.15.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.24.5 (2.24.5-1.fc10) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2746 Lines: 62 On Thu, 2009-06-25 at 11:10 +0200, Jens Axboe wrote: > On Thu, Jun 25 2009, Peter Zijlstra wrote: > > On Wed, 2009-06-24 at 15:27 -0700, Andrew Morton wrote: > > > On Wed, 24 Jun 2009 11:38:24 +0100 > > > Richard Kennedy wrote: > > > > > > > When writing to 2 (or more) devices at the same time, stop > > > > balance_dirty_pages moving dirty pages to writeback when it has reached > > > > the bdi threshold. This prevents balance_dirty_pages overshooting its > > > > limits and moving all dirty pages to writeback. > > > > > > > > > > > > Signed-off-by: Richard Kennedy > > > > --- > > > > Acked-by: Peter Zijlstra > > After doing some integration and update work on the writeback branch, I > threw 2.6.31-rc1, 2.6.31-rc1+patch, 2.6.31-rc1+writeback into the test > mix. The writeback series include this patch as a prep patch. Results > for the mmap write test case: > > Kernel Throughput usr sys ctx util > -------------------------------------------------------------- > vanilla 184MB/sec 19.51% 50.49% 12995 82.88% > vanilla 184MB/sec 19.60% 50.77% 12846 83.47% > vanilla 182MB/sec 19.25% 51.18% 14692 82.76% > vanilla+patch 169MB/sec 18.08% 43.61% 9507 76.38% > vanilla+patch 170MB/sec 18.37% 43.46% 10275 76.62% > vanilla+patch 165MB/sec 17.59% 42.06% 10165 74.39% > writeback 215MB/sec 22.69% 53.23% 4085 92.32% > writeback 214MB/sec 24.31% 52.90% 4495 92.40% > writeback 208MB/sec 23.14% 52.12% 4067 91.68% > > To be perfectly clear: > > vanilla 2.6.31-rc1 stock > vanilla+patch 2.6.31-rc1 + bdi_thresh patch > writeback 2.6.31-rc1 + bdi_thresh patch + writeback series > > This is just a single spindle w/ext4, nothing fancy. I'll do a 3-series > run with the writeback and this patch backed out, to see if it makes a > difference here. I didn't do that initially, since the results were in > the range that I expected. Intriguing numbers. It would tell us a lot if we could find out why vanilla + patch is slower than vanilla. I'll run some tests using mmap and see if I can find anything. What block size are you using ? I see that the last test of each group is the slowest. I wonder if this is showing a slowdown over time or just noise? Any chance you could run more tests in each group? regards Richard -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/