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Re: Re: [PATCH] unified frontend support for pg_malloc et al and palloc/pfree mulation (was xlogreader-v4)

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Andres Freund <andres(at)2ndquadrant(dot)com>
Cc: Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Re: [PATCH] unified frontend support for pg_malloc et al and palloc/pfree mulation (was xlogreader-v4)
Date: 2013-01-13 19:17:52
Message-ID: 22214.1358104672@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Andres Freund <andres(at)2ndquadrant(dot)com> writes:
> the numbers are:
> old definition:                                 10393.658ms, 5497912 bytes
> old definition + unreachable:                   10011.102ms, 5469144 bytes
> stmt, two calls, unreachable:                   10036.132ms, 5468792 bytes
> stmt, one call, unreachable:                    9443.612ms,  5462232 bytes
> stmt, one call, unreachable, save errno:        9615.863ms,  5489688 bytes

I find these numbers pretty hard to credit.  Why should replacing two
calls by one, in code paths that are not being taken, move the runtime
so much?  The argument that a net reduction of code size is a win
doesn't work, because the last case is more code than any except the
first.

I think you're measuring some coincidental effect or other, not a
reproducible performance improvement.  Or there's a bug in the code
you're using.

			regards, tom lane


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Subject: Re: [PATCH] unified frontend support for pg_malloc et al and palloc/pfree mulation (was xlogreader-v4)
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