Re: Dupal Opteron on Sarge
> Another concern is the heat those CPU beasts produce (90W each). You may
> want to find a cooler solution which doesnt grill you or the CPU and also
> doesnt make you death. (I am sitting next to such a beast right now ;-)
>
> Most cooling systems go up to the 246 or 248. Finding one for the 252
> might be difficult. I had a hard time finding a cooler which would do his
> job for the 248 while still allowing me to hear my own voice ;-).
IIRC the 252 has the same thermal rating (89W) as the 246, so the cooling
system should be the same. Even the dual-core chips are only 95W. Most
Opteron cooling systems should be able to cope with any of these. The Zalman
coolers are very quiet and more than capable of coping with these CPUs.
If you're bothered about heat/noise you should probably go for the HE cpus.
These are more expensive, but only generate about half the heat (55W). A
246HE runs exactly the same speed as a regular 246.
You should also look at the Athlon64 X2 CPUs. For many workloads these are
just as good as a dual socket board. Obviously with a dual socket board you
have the option of building a quad-core machine.
> Note that 2xCPU systems are not twice as fast as single CPU systems. The
> SMP setup does have a bit of a overhead on your OS, so expect something
> like 0,8x the speed of a single CPU system.
amd64 systems scale pretty well up to [at least] 4 CPUs. In my experience much
better than Intel systems. I've seen CPU/memory intensive workloads scale
linearly. Obviously if your workload is IO bound throwing more CPUs at it
probably won't help at all.
> What the 2xCPU system gives you however, is the ability to handle heavy
> load. It can handle obviously more requests than a single CPU system. It
> will also take advantage of the hyperthreading bus *communication bus
> between the CPUs.
Hypertransport, not Hyperthreading.
> This means that CPU1 can *borrow Memory from CPU2 if it is required for an
> application.
It's worth noting that even remote memory (ie. attached to the other CPU) is
still closer (lower latency) than system memory on many Intel systems.
Paul
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