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Date: Fri, 10 Nov 2006 22:52:57 -0800
From: Andrew Morton <akpm@...l.org>
To: "Igor A. Valcov" <viaprog@...il.com>
Cc: linux-kernel@...r.kernel.org, xfs@....sgi.com
Subject: Re: XFS filesystem performance drop in kernels 2.6.16+
On Fri, 10 Nov 2006 16:16:27 +0300
"Igor A. Valcov" <viaprog@...il.com> wrote:
> Below is a simplified version of the test program,
Boy, I hope not. The results of this test program are of very little interest.
> for (i = 0; i < 262144; i++) {
> /* Write data to a big file */
> write (nFiles [0], buf, __BYTES);
>
> /* Write data to small files */
> for (f = 1; f < __FILES; f++)
> write (nFiles [f], &f, sizeof (f));
> }
This sits in a loop doing write(fd, buf, 4). This is wildly inefficient -
you'd get a 10x throughput benefit and maybe 100x reduction in CPU cost
simply by switching to fwrite().
I suspect something went wrong here.
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