Messages in this thread | | | Subject | Re: 2.6.11-mm2 | From | Robert Love <> | Date | Tue, 08 Mar 2005 18:44:02 -0500 |
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On Tue, 2005-03-08 at 23:36 +0000, J.A. Magallon wrote:
> Can cpu affinity really be changed for a running process ?
Yes.
> Does it need something like io or yielding to take effect ?
No.
> I am playin with Robert Love's taskset (symlinked to runon, it is easier > to type and I'm more used to it), because I want to play with hyperthreading > and wanted a method to force two threads on the same physical package. > It works fine to bound a new process to a cpu set, but I does not change > anything for a running process. > > I try runon -c -p 0 <pid> for my numbercruncher and it does nothing, top > shows it is in the same cpus where it started: > > werewolf:~# runon -c -p 0 8277 > pid 8277's current affinity list: 0-3 > pid 8277's new affinity list: 0 > werewolf:~# runon -c -p 8277 > pid 8277's current affinity list: 0
This looks fine. As expected.
Although, you have the syntax wrong. It should be
taskset -c 0 -p 8277
and
taskset -p 8277
> The program uses posix threads, 2 in this case. The two threads change from > cpu sometimes (not too often), but do not go into the same processor > immediately as when I start the program directly with runon/taskset.
You have to bind all of the threads individually.
Robert Love
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