X2 and CPU Load Balancing - Affinity Setting

[Duke]

I have an AMD X2 4800+ on an A8N32-SLI board. I also Fold @ 80% CPU utilization (go Team 1714)! I'm wondering if it's better to set Affinity to, say, 1 for the Folding executable, thereby confining it to one CPU only (leaving the other CPU "free"), or not set any Affinity, thus letting the Folding load balance across both CPU's @40% utilization each.

Anyone have any thoughts on which is better?

Duke

[Protoplasm72]

I haven't tried it myself but a quick google search suggests that you might see some minimal gains. It's definately not going to hurt your performance.

[h20-ski]

Just as a note, that the CPU does not load balance between the cores. What happens is that a certain part is assigned to a core and Windows sees that core loaded so it does another on the other core. Although do this at billionths of a second and it appears to be load balancing. As for perfmance gain by setting affinity, not any that you can measure. Also the X2 has a very nice interconnect between the cores so, very little is lost there. And then once the wu is complete it restarts the core (folding) so the affinity you set is now lost.

[Duke]

Originally Posted by h20-ski

Just as a note, that the CPU does not load balance between the cores. What happens is that a certain part is assigned to a core and Windows sees that core loaded so it does another on the other core. Although do this at billionths of a second and it appears to be load balancing. As for perfmance gain by setting affinity, not any that you can measure. Also the X2 has a very nice interconnect between the cores so, very little is lost there. And then once the wu is complete it restarts the core (folding) so the affinity you set is now lost.

Thanks, all. h2o-ski you really helped clarify my question about how a dual core processor juggles the workload between the two cores, which was the origin of my question relative to loading one side or the other with the Folding executable. Good point also on not trying to set affinity, due to core restarts.

Cheers,
Duke

[h20-ski]

I tried it myself on the Server, and I found no major loss or gain from doing so. Although as a note if I am folding with just 2 clients, Windows Server 2k3 sometimes sets affinity by itself just loading 1 client per processor. So maybe Server 2k3 knows something that we don't.