Horton

Re: profiling connection overhead

Peter Eisentraut <peter_e@gmx.net>

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From: Peter Eisentraut <peter_e@gmx.net>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Jeff Janes <jeff.janes@gmail.com>, Andres Freund <andres@anarazel.de>, Robert Haas <robertmhaas@gmail.com>, Bruce Momjian <bruce@momjian.us>, pgsql-hackers@postgresql.org, Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Date: 2010-12-01T05:14:56Z
Lists: pgsql-hackers 
On tis, 2010-11-30 at 15:49 -0500, Tom Lane wrote:
> Peter Eisentraut <peter_e@gmx.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.