Message-ID: <48F3615B.4050705@mochima.com>
Date: Mon, 13 Oct 2008 10:55:23 -0400
From: Carlos Moreno <morenopg@mochima.com>
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To: pgsql-performance@postgresql.org
Subject: Re: "Mysterious" issues with newly installed 8.3
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Thanks Greg and others for your replies,

> This is really something to watch out for.  One quick thing first
> though: what frequency does the CPU on the new server show when you
> look at /proc/cpuinfo?  If you see "cpu MHz:  1000.00" 

It was like that in the initial setup --- I just disabled the cpuspeed
service  (service cpuspeed stop;  chkconfig cpuspeed off ), and now
it shows the full 2600MHz at all times  (the installation of PG was
done after this change)

> Another really handy way to gauge memory speed on Linux, if there are
> similar kernels installed on each system like your case, is to use
> "hdparm -T".

Great tip!  I was familiar with the -T switch, but was not clear on the
notion that the figure tells you that much about the overall memory
performance!

Anyway, I checked on both, and the new system is slightly superior
(around 2200 for the new, around 1900 for the old one) --- a bit below
the figure you mention you'd expect  (2500 --- though that was for a
2.8GHz Opteron, presumably with faster FSB and faster memory??)

I guess my logical next step is what was suggested by Scott --- install
8.2.4 and repeat the same tests with this one;  that should give me
interesting information.

Anyway, if I find something interesting or puzzling, I would post again
with the results of those tests.

Thanks again for the valuable advice and comments!

Carlos
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