Re: [ACPI] Re: [RFC 5/6]clean cpu state after hotremove CPU

Nathan Lynch
2005-04-05T00:13:31Z

Hi Nigel!

On Tue, Apr 05, 2005 at 08:14:25AM +1000, Nigel Cunningham wrote:
>
> On Tue, 2005-04-05 at 01:33, Nathan Lynch wrote:
> > > Yes, exactly. Someone who understand do_exit please help clean up the
> > > code. I'd like to remove the idle thread, since the smpboot code will
> > > create a new idle thread.
> >
> > I'd say fix the smpboot code so that it doesn't create new idle tasks
> > except during boot.
>
> Would that mean that CPUs that were physically hotplugged wouldn't get
> idle threads?

No, that wouldn't work. I am saying that there's little to gain by
adding all this complexity for destroying the idle tasks when it's
fairly simple to create num_possible_cpus() - 1 idle tasks* to
accommodate any additional cpus which may come along. This is what
ppc64 does now, and it should be feasible on any architecture which
supports cpu hotplug.

Nathan

* num_possible_cpus() - 1 because the idle task for the boot cpu is
created in sched_init.