Re: CPU Hotplug: Hotplug Script And SIGPWR

[Nick Piggin]

Tim Hockin wrote:

> On Tue, Jan 20, 2004 at 05:43:59PM +1100, Nick Piggin wrote:
>
> > > I think the sanest thing for a CPU removal is to migrate everything off the
> > > processor in question, move unrunnable tasks into TASK_UNRUNNABLE state,
> > > then notify /sbin/hotplug.  The hotplug script can then find and handle the
> > > unrunnable tasks.  No SIGPWR grossness needed.
> > >
> > > Code against 2.4 at http://www.hockin.org/~thockin/procstate - it was
> > > heavily tested and I *think* it is all correct (for that kernel snapshot).
> > Seems less robust and more ad hoc than SIGPWR, however.
>
> Disagree.  SIGPWR will kill any process that doesn't catch it.  That's
> policy.  It seems more robust to let the hotplug script decide what to do.
> If it wants to kill each unrunnable task with SIGPWR, it can.  But if it
> wants to let them live, it can.

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 dropped lhcs-devel@xxxxxxxxxxxxxxxxxxxxx because its moderated)


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/