Re: gprof SELECT COUNT(*) results

[Olivier Thauvin <olivier(dot)thauvin(at)aerov(dot)jussieu(dot)fr>]

Le Vendredi 25 Novembre 2005 16:20, Tom Lane a écrit :
> 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 that what you're looking for ?

[thauvin(at)samsufi ~]$ egrep "(model name|MHz)" /proc/cpuinfo
model name      : AMD Opteron(tm) Processor 250
cpu MHz         : 2391.040
model name      : AMD Opteron(tm) Processor 250
cpu MHz         : 2391.040

$ cat /etc/mandrake-release
Mandrakelinux release 10.1 (Community) for x86_64

I can try to backport Postgresql 8.1.0 rpms from developement tree on mandriva 
10.1, install and run some test if you're really interested.

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