Re: current linux-2.6.git: cpusets completely broken

From: Ingo Molnar
Date: Sun Jul 13 2008 - 14:19:46 EST



* Dmitry Adamushko <dmitry.adamushko@xxxxxxxxx> wrote:

> > So instead of this illogical and crazy mess:
> >
> > + switch (phase) {
> > + case CPU_UP_CANCELED:
> > + case CPU_UP_CANCELED_FROZEN:
> > + case CPU_DOWN_FAILED:
> > + case CPU_DOWN_FAILED_FROZEN:
> > + case CPU_ONLINE:
> > + case CPU_ONLINE_FROZEN:
> > + case CPU_DEAD:
> > + case CPU_DEAD_FROZEN:
> > + common_cpu_mem_hotplug_unplug(1);
> >
> > it should just say
> >
> > + switch (phase) {
> > + case CPU_ONLINE:
> > + case CPU_ONLINE_FROZEN:
> > + case CPU_DEAD:
> > + case CPU_DEAD_FROZEN:
> > + common_cpu_mem_hotplug_unplug(1);
> >
> > because it only makes sense to rebuild the scheduler domains when the
> > thing SUCCEEDS.
> >
> > See? By having a sane design, the code is not just more robust and
> > easy to follow, you can also simplify it and make it more logical.
>
> Yes, I agree. And I did _not_ say that the current design is sane. My
> impression about changes acceptable during a late release cycle was
> utterly CRAPPY (indeed, it's always better to immediately fix a
> problem the right way, not just add another patch and pray it doesn't
> break somewhere else).

mind sending Linus's patch as a completed patchset against tip/master
(or tip/sched/devel) so that we can do it in early v2.6.27?

i still think your cpusets.c fix is what we should do for v2.6.26, given
that there's agreement about how to fix it for real and thus in terms of
regression/bug risk your patch is lower-impact and CPU hotplug has been
broken for such a long time.

But we should follow it up with Linus's patch immediately afterwards in
v2.6.27. Hm?

Ingo
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