Re: test_fsync file overrun

Jeff Janes wrote:
> test_fsync in tools/fsync pre-creates a 16MB file. If it is given a number
> of iterations greater than 1024 (like one might use if trying to see what
> happens when NVRAM gets filled, or on a journaling file system), than one of
> the writes being timed will have to extend the size of the pre-created test
> file, which can greatly skew the results.
>
> This patch uses lseek to periodically restart at the beginning of the file,
> rather than writing past the end of it.

Oh, I never noticed that the later tests kept appending to the file
rather then overwriting it. I have applied the attached fix for CVS
HEAD that just uses lseek() before each write group, as you suggested.
I have backpatched it to 8.4.X because the original code created 16GB
files in tests (yikes).

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Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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