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

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Date:	Mon, 18 Apr 2016 19:55:32 +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 Mon, 2016-04-18 at 19:15 +0200, Sebastian Andrzej Siewior wrote:

> take 2. There is this else case in pin_current_cpu() where I take
> hp_lock. I didn't manage to get in there. So I *think* we can get rid of
> the lock now. Since there is no lock (or will be) we can drop the whole
> `do_mig_dis' checking and do the migrate_disable() _after_ we obtained
> the lock. We were not able to do so due to the lock hp_lock.
> 
> And with this, I didn't manage to triger the lockup you had with
> futextest.

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..

	-Mike