Re: CPU Hotplug: Hotplug Script And SIGPWR

Nick Piggin
2004-01-21T04:19:28Z

Srivatsa Vaddagiri wrote:

>On Tue, Jan 20, 2004 at 12:43:52AM -0800, Tim Hockin wrote:
>
>>IFF the app is designed to handle it. The existence of a SIGPWR handler
>>does not necessarily imply that, though. a SIGCPU or something might
>>correlate 1:1 with this, but SIGPWR doesn't.
>>
>
>I agree we should have a separe signal for CPU Hotplug. By default the signal
>will be ignored, unless a task registers a signal handler for that special
>signal.
>

I'd be happy with that.

>
>That way, tasks which "knowingly" change their CPU affinity will be able to
>tackle a CPU going down by handling the signal (probably change their CPU
>affinity again), while tasks which have their CPU affinity changed "unknowingly"
>(by other tasks) will just ignore the signal. The hotplug script interface
>allows the admin to go and change the CPU affinity again for the second class
>of tasks, if needed.
>

Yes, that is with the cpu-is-down hotplug event, right?

*Before* that happens, tasks that don't handle the signal should just
have their affinity changed to all cpus.

Or doesn't anybody care to think about hoplug scripts failing?
(serious question)