Re: testing ProcArrayLock patches

From: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
To: "Andres Freund" <andres(at)anarazel(dot)de>
Cc: "Robert Haas" <robertmhaas(at)gmail(dot)com>, <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: testing ProcArrayLock patches
Date: 2011-11-18 20:16:01
Message-ID: 4EC668A10200002500043257@gw.wicourts.gov
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Andres Freund <andres(at)anarazel(dot)de> wrote:

> When doing line-level profiles I would suggest looking at the
> instructions.

What's the best way to do that?

> I don't think cache line contention is the most likely candidate
> here. Simple cache-misses seem far more likely. In combination
> with pipeline stalls...
>
> Newer cpus (nehalem+) can measure stalled cycles which can be
> really useful when analyzing performance. I don't remember how to
> do that with oprofile right now though as I use perf these days
> (its -e stalled-cycles{frontend|backend} there}).

When I run oprofile, I still always go back to this post by Tom:

http://archives.postgresql.org/pgsql-performance/2009-06/msg00154.php

Can anyone provide such a "cheat sheet" for perf? I could give that
a try if I knew how.

-Kevin

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