F@H on dual processors

[bunker]

Is it necessary to set affinity when running two instances of F@H on a dual processor machine?

I've been doing it manually in task manager just to make sure, but is it necessary? And if so, how the heck do I do it automatically?

 

[kb3edk]

Originally posted by: bunker
Is it necessary to set affinity when running two instances of F@H on a dual processor machine?

I've been doing it manually in task manager just to make sure, but is it necessary? And if so, how the heck do I do it automatically?

Typically what I do when running F@H on SMP systems is have two separate folders "F@H" and "F@H2", each with the console mode F@H client installed. Each instance gets its own shortcut on my desktop. Then the execution string for each instance is something line "D:\Program Files\Folding@Home\FAH502-Console.exe" -local -advmethods". The key is the -local flag, without it the clients get confused with each other!

Anyway that's how I do it, I bet some other people here have more sophisticated ways (such as how to do this with the GUI client, or how to get this to work in Service mode, or on Linux). Hope this helps -

-Adam

EDIT: I did a little more research on processor affinity and saw that it's more complex than I had thought. It looks like it's a way of keeping a particular F@H instance crunching on a specific CPU (#0, #1, etc.) Anyway I think when you run the console mode client for the first time, it prompts you for a Machine ID, I seem to recall typing in a different digit for each instance. So no, you should not need to set an affinity each time, the client should "remember" which CPU it's supposed to run on.

 

[bunker]

I remember setting the machineID as well for each instance. I'll set up a shortcut with the -local as well. (I left off -advmethods as they are only 800mhz processors)

 

[Insidious]

unfortunately, the machineID will not set affinity for F@H. You don't really need to. If you run two instances (from two different folders, with two different IDs set) you will be fine. You won't necessarily have each WU working on only one CPU but the sharing overhead is VERY small.

Before I stopped F@H, I experimented, and observed that they were spread over both CPUs, but setting affinity did not changed PPD at all.

hope this helps

Sid

(If you are running one instance of F@H and one instance of something else such as a BOINC project, you DO need to set affinity or F@H will hog more resource than it's one CPU core. (I saw it get as bad ad 75/25)

But again.... MachineID does not set affinity nor does the -local flag (it just tells F@H where to look for it's files)