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Message-ID: <20090625124342.GN31415@kernel.dk> Date: Thu, 25 Jun 2009 14:43:42 +0200 From: Jens Axboe <jens.axboe@...cle.com> To: Al Boldi <a1426z@...ab.com> Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>, Andrew Morton <akpm@...ux-foundation.org>, Richard Kennedy <richard@....demon.co.uk>, linux-mm@...ck.org, linux-kernel@...r.kernel.org Subject: Re: [RFC][PATCH] mm: stop balance_dirty_pages doing too much work On Thu, Jun 25 2009, Al Boldi wrote: > Jens Axboe wrote: > > On Thu, Jun 25 2009, 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 <richard@....demon.co.uk> 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 <richard@....demon.co.uk> > > > > > > --- > > > > > > > > Acked-by: Peter Zijlstra <a.p.zijlstra@...llo.nl> > > > > > > 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. > > > > Results for writeback without the bdi_thresh patch > > > > Kernel Throughput usr sys ctx util > > -------------------------------------------------------------- > > wb-bdi_thresh 211MB/sec 22.71% 53.30% 4050 91.19% > > wb-bdi_thresh 212MB/sec 22.78% 53.55% 4809 91.51% > > wb-bdi_thresh 212MB/sec 22.99% 54.23% 4715 93.10% > > > > Not a lot of difference there, without more than three runs it's hard to > > say what is significant. Could be a small decrease in throughput, if the > > 208MB/sec results from above is an outlier (I think it is, ~215MB/sec is > > usually the most consistent result). > > What's the iowait on these runs? Not sure, I didn't check. Why do you ask? -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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