Subject: Re: CVS commit: pkgsrc/benchmarks/bytebench
To: Urban Boquist <firstname.lastname@example.org>
From: Todd Vierling <email@example.com>
Date: 11/01/2005 22:16:27
On Tue, 1 Nov 2005, Urban Boquist wrote:
> Todd> While there, use fsync(2) on all hosts. Without this, the
> Todd> fstime benchmark will be disproportionately biased toward OS's
> Todd> and hardware that buffer larger amounts of data in memory before
> Todd> [background] syncing.
> the second part of this change seems inappropriate, IMHO. The
> benchmark may be biased, but that is not up to pkgsrc to
> decide. Pkgsrc is just supposed to be a way to port software, it
> should not change the behavior of an old and well defined benchmark.
Actually, I just disproved fstime's methodology. Without using fsync(2),
the numbers are *meaningless*. Testing filesystem speed accurately requires
actually writing to the disk -- and if you don't fsync(2), you can very well
end up with a "write speed" of one or two orders of magnitude higher than a
disk is physically capable of performing.
It should wither get fsync(2), or be removed from the battery of tests. We
should not be providing a bogus test in a supplied benchmark program.
-- Todd Vierling <firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org>