Re: CPU Hotplug: Hotplug Script And SIGPWR

Tim Hockin
2004-01-20T07:30:42Z

On Tue, Jan 20, 2004 at 06:11:49PM +1100, Nick Piggin wrote:
> I thought hotplug is allowed to fail? Thus you can have a hung system.
> Or what if the hotplug script itself becomes TASK_UNRUNNABLE? What if the
> process needs a guaranteed scheduling latency?

I guess a hotplug script MAY fail. I don't think it's a good idea to make
your CPU hotplug script fail. May and Misght are different. It's up to the
implementor whether the script can get into a failure condition.

The hotplug script can only become unrunnable if you yank out all the CPUs
on the system. I'd assume it would have an affinity of 0xffffffff.

What if <which> process needs guaranteed scheduling latency? Do we really
_guarantee_ scheduling latency *anywhere*?