Hi-
Ingo Molnar wrote:
>
> * Cliff Wickman <[EMAIL PROTECTED]> wrote:
>
> > With this patch, migrate the task to:
> > 1) to any cpu on the same node as the disabled cpu, which is both online
> > and among that task's cpus_allowed
> > 2) to any online cpu within the task's cpuset
> > 3) to any cpu which is both online and among that task's cpus_allowed
> >
> > Diffed against 2.6.21-rc3 (Andrew's current top of tree)
>
> looks good to me.
>
> Acked-by: Ingo Molnar <[EMAIL PROTECTED]>
>
> > + /* try to stay on the same cpuset */
> > + if (dest_cpu == NR_CPUS) {
> > + p->cpus_allowed = cpuset_cpus_allowed(p);
> > + dest_cpu = any_online_cpu(p->cpus_allowed);
> > + }
>
> what's the practical effect of this - when moving the last CPU offline
> from a node you got jobs migrated to really alien nodes? Thus i think we
> should queue this up for v2.6.21 too, correct? It's a NOP on systems
> that do not set up cpusets, so it's low-risk.
See my earlier reply to this patch. Calling cpuset_cpus_allowed
(which takes a mutex) here is a bug, since move_task_off_dead_cpu must
be called with interrupts disabled.
> btw., unrelated to your patch, there's this bit right after the code
> above:
>
> /* No more Mr. Nice Guy. */
> if (dest_cpu == NR_CPUS) {
> rq = task_rq_lock(p, &flags);
> cpus_setall(p->cpus_allowed);
> dest_cpu = any_online_cpu(p->cpus_allowed);
>
> out of consistency, shouldnt the cpus_setall() rather be:
>
> p->cpus_allowed = cpu_possible_map;
>
> ? It shouldnt make any real difference but it looks more consistent.
The default value of cpus_allowed is CPU_MASK_ALL, I thought -- at
least that's what we set init's to early on. Though, as you say, it
shouldn't make any difference.
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