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Re: pgbench cpu overhead (was Re: lazy vxid locks, v1)

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
Cc: Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc>, pgsql-hackers(at)postgresql(dot)org, Robert Haas <robertmhaas(at)gmail(dot)com>
Subject: Re: pgbench cpu overhead (was Re: lazy vxid locks, v1)
Date: 2011-07-24 15:46:49
Message-ID: 12391.1311522409@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Jeff Janes <jeff(dot)janes(at)gmail(dot)com> writes:
> How was this profile generated?  I get a similar profile using
> --enable-profiling and gprof, but I find it not believable.  The
> complete absence of any calls to libpq is not credible.  I don't know
> about your profiler, but with gprof they should be listed in the call
> graph even if they take a negligible amount of time.  So I think
> pgbench is linking to libpq libraries that do not themselves support
> profiling (I have no idea how that could happen though).  If the calls
> graphs are not getting recorded correctly, surely the timing can't be
> reliable either.

Last I checked, gprof simply does not work for shared libraries on
Linux --- is that what you're testing on?  If so, try oprofile or
some other Linux-specific solution.

			regards, tom lane

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