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Message-Id: <20070516133726.0c68a65f.akpm@linux-foundation.org> Date: Wed, 16 May 2007 13:37:26 -0700 From: Andrew Morton <akpm@...ux-foundation.org> To: Chris Mason <chris.mason@...cle.com> Cc: Chuck Ebbert <cebbert@...hat.com>, linux-kernel@...r.kernel.org Subject: Re: filesystem benchmarking fun On Wed, 16 May 2007 16:14:14 -0400 Chris Mason <chris.mason@...cle.com> wrote: > On Wed, May 16, 2007 at 01:04:13PM -0700, Andrew Morton wrote: > > > The good news is that if you let it run long enough, the times > > > stabilize. The bad news is: > > > > > > create dir kernel-86 222MB in 15.85 seconds (14.03 MB/s) > > > create dir kernel-87 222MB in 28.67 seconds (7.76 MB/s) > > > create dir kernel-88 222MB in 18.12 seconds (12.27 MB/s) > > > create dir kernel-89 222MB in 19.77 seconds (11.25 MB/s) > > > > well hang on. Doesn't this just mean that the first few runs were writing > > into pagecache and the later ones were blocking due to dirty-memory limits? > > > > Or do you have a sync in there? > > > There's no sync, but if you watch vmstat you can clearly see the log > flushes, even when the overall create times are 11MB/s. vmstat goes > 30MB/s -> 4MB/s or less, then back up to 30MB/s. How do you know that it is a log flush rather than, say, pdflush hitting the blockdev inode and doing a big seeky write? - 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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