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

From	Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Newsgroups	linux.kernel
Subject	Re: [rfc patch] hotplug: Call mmdrop_delayed() in sched_cpu_dying() if PREEMPT_RT_FULL
Date	2016-10-20 13:30 +0200
Message-ID	<sujHP-6Ry-15@gated-at.bofh.it> (permalink)
References	<spcH2-6dt-141@gated-at.bofh.it> <suhZn-5G9-23@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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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

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[rfc patch] hotplug: Call mmdrop_delayed() in sched_cpu_dying() if  PREEMPT_RT_FULL Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-10-20 11:40 +0200
  Re: [rfc patch] hotplug: Call mmdrop_delayed() in sched_cpu_dying()  if PREEMPT_RT_FULL Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-10-20 13:30 +0200

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