Re: Value of Quad vs. Dual Processor machine

On Wed, 2003-11-12 at 09:28, Jeff wrote:
> On Tue, 11 Nov 2003 21:13:19 -0500
> "Chris Field" <cfield@affinitysolutions.com> wrote:
>
> > we are looking at Xeon, We are currently running it on a quad sun v880
> > compiled to be 64bit and have been getting dreadful performance.  I
> > don't think we really have much to gain from going 64bit.
> >
> >
> By chance, are you running 7.3.4 on that sun?
> If so, try this:
> export CFLAGS=-02
> ./configure
>
> and rebuild PG.
>
> Before 7.4 PG was build with _no_ optimization on Solaris.
> Recompiling gives __HUGE__ (notice the underscores) performance gains.
>
> And onto the dual vs quad.
>
> PG will only use 1 cpu / connection / query.
>
> So if your machine iwll have 1-2 queries running at a time those other 2
> proc's will sit around idling.  However if you are going to have a bunch
> going, 4 cpus will be most useful.  One of hte nicest things to do for
> PG is more ram and fast IO. It really loves those things.
>

We've just started kicking around the idea of moving one of our boxes to
a quad-proc machine from a dual. Under normal circumstances the 2
processors handle maybe 200 transactions per second with 90% system
idle.  However we have people who occasionally run historical reports on
our data, and those reports are fairly CPU intensive. Usually it is not
a problem for the main web system, but when pg_dump is running, that is
also cpu intensive, so we end up with two highly cpu intensive items
running on our machine, and we start to notice issues on the main web
system.


Robert Treat
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