linux-kernel - Re: [PATCH RT 4/6] rt/locking: Reenable migration accross schedule

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Date:	Tue, 19 Apr 2016 10:55:00 +0200
From:	Mike Galbraith <umgwanakikbuti@...il.com>
To:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	linux-rt-users@...r.kernel.org, linux-kernel@...r.kernel.org,
	Steven Rostedt <rostedt@...dmis.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH RT 4/6] rt/locking: Reenable migration accross schedule

On Tue, 2016-04-19 at 09:07 +0200, Sebastian Andrzej Siewior wrote:
> On 04/18/2016 07:55 PM, Mike Galbraith wrote:
> > 
> > I'll have to feed it to DL980, hotplug and jitter test it.  It seemed
> > to think that pinning post acquisition was a bad idea jitter wise, but
> > I was bending things up while juggling multiple boxen, so..
> 
> pinning pre acquisition could get you in a situation where you get the
> lock and you are stuck on CPU A where is also a task running right now
> with a higher priority while CPU B and CPU C are idle.

I can't get to my DL980 to do jitter testing atm (network outage), but
wrt hotplug banging, my local boxen say patch is toxic.  i4790 desktop
box silently bricked once too.  The boom begins with...

   BUG: scheduling while atomic: futex_wait/11303/0x00000000

...very noisy funeral procession follows.

	-Mike