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Wu Fengguang authored
Enlarge default dirty ratios from 5/10 to 10/20. This fixes [Bug #12809] iozone regression with 2.6.29-rc6. The iozone benchmarks are performed on a 1200M file, with 8GB ram. iozone -i 0 -i 1 -i 2 -i 3 -i 4 -r 4k -s 64k -s 512m -s 1200m -b tmp.xls iozone -B -r 4k -s 64k -s 512m -s 1200m -b tmp.xls The performance regression is triggered by commit 1cf6e7d8(mm: task dirty accounting fix), which makes more correct/thorough dirty accounting. The default 5/10 dirty ratios were picked (a) with the old dirty logic and (b) largely at random and (c) designed to be aggressive. In particular, that (a) means that having fixed some of the dirty accounting, maybe the real bug is now that it was always too aggressive, just hidden by an accounting issue. The enlarged 10/20 dirty ratios are just about enough to fix the regression. [ We will have to look at how this affects the old fsync() latency issue, but that probably will need independent work. - Linus ] Cc: Nick Piggin <npiggin@suse.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Reported-by:
"Lin, Ming M" <ming.m.lin@intel.com> Tested-by:
"Lin, Ming M" <ming.m.lin@intel.com> Signed-off-by:
Wu Fengguang <fengguang.wu@intel.com> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
1b5e62b4