Re: [rfc patch] hotplug: Call mmdrop_delayed() in sched_cpu_dying() if PREEMPT_RT_FULL

[Sebastian Andrzej Siewior]

On 2016-10-20 11:34:03 [+0200], Mike Galbraith wrote:
> My 64 core box just passed an hour running Steven's hotplug stress
> script along with stockfish and futextests (tip-rt.today w. hotplug
> hacks you saw a while back), and seems content to just keep on grinding
> away.  Without it, box quickly becomes a doorstop.

This is new. It is v4.7-rc1 new. The hotplug rework moved the notified
around and after

e9cd8fa4fcfd ("sched/migration: Move calc_load_migrate() into CPU_DYING")
f2785ddb5367 ("sched/hotplug: Move migration CPU_DYING to sched_cpu_dying()")

we have no more CPU_DEAD, just CPU_DYING which is invoked with
interrupts off. I don't see anything wrong with pushing this over to
RCU.

Sebastian