Re: profile-guided opt. w/ GCC

From: Neil Conway <neilc(at)samurai(dot)com>
To: Peter Eisentraut <peter_e(at)gmx(dot)net>
Cc: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: profile-guided opt. w/ GCC
Date: 2004-09-30 10:12:07
Message-ID: 1096539127.25277.396.camel@localhost.localdomain
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On Thu, 2004-09-30 at 19:49, Peter Eisentraut wrote:
> I doubt that the regression tests are anywhere near representative input
> data. They run a proportion of borderline and error cases that is much
> higher than I would expect in normal use.

That's definitely true. At first glance, the regression tests don't seem
to be *too* badly skewed:

[src/test/regress/expected]% grep ERROR *.out | wc -l
867
[src/test/regress/expected]% grep -i "^SELECT" *.out | wc -l
2924
[src/test/regress/expected]% grep -i "^INSERT" *.out | wc -l
2714
[src/test/regress/expected]% grep -i "^UPDATE" *.out | wc -l
122
[/src/test/regress/expected]% grep -i "^DELETE" *.out | wc -l
110
[src/test/regress/expected]% grep -i "^CREATE" *.out | wc -l
848
[src/test/regress/expected]% grep -i "^COPY" *.out | wc -l
46

I guess it depends on how closely the test data needs to match "normal"
input data for the gcc optimizer to be able to make valid decisions. My
intuition is that the regression tests are sufficiently close to normal
input that it won't be an issue, but I'm not sure.

-Neil

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