Re: CPU Hotplug: Hotplug Script And SIGPWR

[Rusty Russell]

In message <20040120075409.GA13897@xxxxxxxxxx> you write:
> Basically, RT tasks + CPU affinity + hotplug CPUs do not play nicely
> together.  I don't see much that can be done to solve that.  With the
> procstate stuff I did, and with planned CPU unplugs we *do* have time before
> the CPU really goes offline in which to act.  With unplanned CPU offlining,
> we don't.

This can't be done with the hotplug scripts.  I originally ran hotplug
synchronous before taking the CPU offline, and Greg KH said that
constitutes abuse 8(

Userspace can agree on a protocol *before* initiating the offline, of
course, in which case it's not a kernel problem.

You make an excellent point though: if you need 2 cpus on your system
to meet requirements, and you go down to one cpu, you have a problem.
But I think that's a "don't do that".

Thanks,
Rusty.
--
  Anyone who quotes me in their sig is an idiot. -- Rusty Russell.
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