Re: gprof SELECT COUNT(*) results

From: "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Qingqing Zhou <zhouqq(at)cs(dot)toronto(dot)edu>, Simon Riggs <simon(at)2ndquadrant(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: gprof SELECT COUNT(*) results
Date: 2005-11-29 00:34:45
Message-ID: 20051129003444.GQ78939@pervasive.com
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On Fri, Nov 25, 2005 at 10:20:11AM -0500, Tom Lane wrote:
> Qingqing Zhou <zhouqq(at)cs(dot)toronto(dot)edu> writes:
> > I can see your computer is really slow, so my theory is that since it is
> > easy to hold a running-slowly horse than a fast one, so my spinlock on a
> > 2.4G modern machine should takes relatively longer time to get effective.
> > Just kidding.
>
> Is that "modern machine" a Xeon by any chance? We know that Xeons have
> fairly awful concurrent performance, and the long latency for bus lock
> instructions may well be the reason why. FWIW, the numbers I showed
> last night were for an HPPA machine, which I used just because I chanced
> to have CVS tip already built for profiling on it. I've since
> reproduced the test on a spiffy new dual Xeon that Red Hat just bought
> me :-) ... and I get similar numbers to yours. It'd be interesting to
> see the results from an SMP Opteron, if anyone's got one handy.

Is there still interest in this? I've got a dual Opteron running FBSD.
(What would be the profiler to use on FBSD?)
--
Jim C. Nasby, Sr. Engineering Consultant jnasby(at)pervasive(dot)com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461

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