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

[Dmitry Adamushko]

2008/7/13 Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>:
>
>> (A little pet horse for the occasion: Testing can show the presence of
>> errors, but not their absence. But that's a different story.)
>
> Absolutely. Which is actually why I prefer my patch. I think it fixes - in
> general - the issue of CPU migration migrating tasks back to the CPU that
> we're taking down.
>
> The other patches seem to work around just the problem that _triggers_ the
> bug. They don't actually make it impossible to migrate to a CPU that is
> getting shut down - they just try to avoid the particular sequence that
> made it happen for you.

Well, they try to make sched-domains consistent for all possible
cases, not just any particular case. So no, they don't allow a
possibility to leave tasks on a dead CPU (unless there is another
bug).

With your patch (and a cpusets :: hotplug handler from the current
-git) sched-domains are still broken and they are used in a number of
places. So why keep them at all?

I'm really surprised that Vegard says this "cpu_active_map" patch
alone fixes the problem.

With your modifications of common_cpu_mem_hotplug_unplug() - yes but
then it will work even without "cpu_active_map".

(ok, unless I'm really blind at this late hour so please direct me to
the right way :-)


>
>                        Linus
>


-- 
Best regards,
Dmitry Adamushko
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