[Beowulf] Re: Opteron 275 performance

[Kozin, I (Igor)]

>   http://multicore.amd.com/WhatIsMC/

That was fun. Thanks Robert! No music though :(
It seems there is an increasingly dominating opinion that the second 
core is meant to run anti-virus protection software 24 hours a day.
 
> I honestly think that the only way to be SURE your particular
> application fits in the probably very broad category of applications
> that can scale from one to four cores in nearly constant time 
> is to try it. 

I absolutely and unequivocally agree with this.

> >> >> We are considering getting a Dual Dual-Core Opteron system vs. two Dual
> >> >> Opteron systems.  We like the ability to use all four cores on one model
> >> >> but a lot of what we'll do is have two models running at the same time,
> >> >> each using two cores.  
> >> >> 
> >> >> We are worried that running two models on one system with four cores (each
> >> >> model using two cores) will not work as well as using two systems, each
> >> >> with two cores/cpu's.  Is this what you were refering to (Igor) when you
> >> >> wrote:
> >> >> 
> >> >>>But I doubt you want to let the idle cores to do something else
> >> >>>in the mean time. 
> >> >> 
> >> >> We have an 8 CPU SGI Origin 3200 that has no problem doing this sort of
> >> >> thing.  I'm just curious what the implications are of doing this with the
> >> >> Dual Core Opteron cpu's.  

In your Origin system a pair of cpus is connected to memory via a router chip.
If by "no problem" you mean that your applications run on 0,2,4,6 processors
as good as on 0,1,2,3 then the chances are good that a dual core Opteron
will be fine too. 
Dual dual-core will also give you a single system image which you are probably
used to on the Origin. E.g. Sun offers Opteron based workstations.
On the other hand two single-core duals will most likely have higher raw 
performance for the same money (albeit higher electricity bill).
You can connect them using a cross-wire and enter the world of clustering!

> >> >> Thanks,
> >> >> 
> >> >> Steve 
> >> >> 

Good luck,
Igor