Re: [PATCH] cpuhotplug: introduce try_get_online_cpus() take 2

Gautham R Shenoy
2009-06-08T04:19:59Z

Hi Paul,

On Fri, Jun 05, 2009 at 08:37:14AM -0700, Paul E. McKenney wrote:
>
> One question for Gautham Shenoy -- are non-atomic CPU-hotplug notifiers
> always invoked from the task that did the cpu_hotplug_begin()?

Except for the notifiers handling two events, rest of the notifiers
are always invoked from the task that did the cpu_hotplug_begin().

The two events are CPU_DYING which is called from the context of the
stop_machine_thread and CPU_STARTING which is called from the context of
the idle thread on the CPU that has just come up. The notifiers handling
these two events are expected to be atomic.

> If so, well and good. If not, then it would not be possible to
> expedite RCU grace periods from within CPU-hotplug notifiers.

I hope this would be good enough :-)
>
> Thanx, Paul
>

--
Thanks and Regards
gautham