[AG-DEV] why is CPU Affinity restricted to the first processor?

[Thomas D. Uram]

I added that after seeing very poor performance from vic on machines with
multiple processors, and being told that vic internal state didn't handle
threading across multiple processors well.  It looks like that is less 
true than
was represented to me at the time.  In any case, that should have been an
option, not a hard-coded change, so we'll make it so for the next release.

I've submitted it here:

http://bugzilla.mcs.anl.gov/accessgrid/show_bug.cgi?id=1638

Tom


On 3/19/07 12:05 PM, Ed Brannin wrote:
> Hello,
>
> I'm running a Dell "Pentium(R) D 3.46GHz" system with...  well, I'm 
> not sure
> if it has multiple CPUs or just Hyperthreading, but the Task Manager 
> shows 4
> CPU usage graphs.
>
> Last week, we had some trouble with dropped packets -- and as it 
> turned out,
> it was partly because all the AG-related processes were starving each 
> other
> on CPU #0.  Manually enabling the CPU affinity to use all CPUs for each
> pythonw, dvts, vlc, vic, etc. process brought that problem under 
> control, so
> I'm wondering: why does AG restrict itself to one CPU under win32?
>
> I see this happens in AccessGrid/Platform/win32/Config.py:555-572, and 
> was
> added by Tom Uram in January 2006 -- but I haven't been able to find any
> discussion of why with Google, the mailing list search or Bugzilla.
>
> Would it be possible to spread processes across each CPU, or even 
> leave them
> with the default CPU affinity?
>
> -Ed Brannin
> edbrannin at gmail.com
>