Re: profiling connection overhead

From: Peter Eisentraut <peter_e(at)gmx(dot)net>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Robert Haas <robertmhaas(at)gmail(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, pgsql-hackers(at)postgresql(dot)org, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
Subject: Re: profiling connection overhead
Date: 2010-12-01 05:14:56
Message-ID: 1291180496.601.1.camel@vanquo.pezone.net
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On tis, 2010-11-30 at 15:49 -0500, Tom Lane wrote:
> Peter Eisentraut <peter_e(at)gmx(dot)net> writes:
> > On mån, 2010-11-29 at 13:10 -0500, Tom Lane wrote:
> >> Rolling in calloc in place of
> >> malloc/memset made no particular difference either, which says that
> >> Fedora 13's glibc does not have any optimization for that case as I'd
> >> hoped.
>
> > glibc's calloc is either mmap of /dev/zero or malloc followed by memset.
>
> Hmm. I would have expected to see a difference then. Do you know what
> conditions are needed to cause the mmap to be used?

Check out the mallopt(3) man page. It contains a few tunable malloc
options that may be useful for your investigation.

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