Re: [ANNOUNCE] 3.14-rt1

From: Mike Galbraith <umgwanakikbuti@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	linux-rt-users <linux-rt-users@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	John Kacur <jkacur@redhat.com>,
	Clark Williams <williams@redhat.com>
Subject: Re: [ANNOUNCE] 3.14-rt1
Date: Wed, 30 Apr 2014 09:43:13 +0200	[thread overview]
Message-ID: <1398843793.26071.52.camel@marge.simpson.net> (raw)
In-Reply-To: <20140429201308.63292691@gandalf.local.home>

On Tue, 2014-04-29 at 20:13 -0400, Steven Rostedt wrote: 
> On Tue, 29 Apr 2014 07:21:09 +0200
> Mike Galbraith <umgwanakikbuti@gmail.com> wrote:
> 
> > On Mon, 2014-04-28 at 16:37 +0200, Mike Galbraith wrote: 
> > 
> > > > Seems that migrate_disable() must be called before taking the lock as
> > > > it is done in every other location.
> > > 
> > > And for tasklist_lock, seems you also MUST do that prior to trylock as
> > > well, else you'll run afoul of the hotplug beast.
> > 
> > Bah.  Futzing with dmesg while stress script is running is either a very
> > bad idea, or a very good test.  Both virgin 3.10-rt and 3.12-rt with new
> > bugs squashed will deadlock.
> > 
> > Too bad I kept on testing, I liked the notion that hotplug was solid ;-)
> 
> I was able to stress cpu hotplug on 3.12-rt after applying the
> following patch.
> 
> If there's no complaints about it. I'm going to add this to the 3.12-rt
> stable tree. As without it, it fails horribly with the cpu hotplug
> stress test, and I wont release a stable kernel that does that.

My local boxen are happy, 64 core box with 14-rt seems happy as well,
though I couldn't let it burn for long.

BTW, that dmesg business went into hiding.  I didn't have time to put
virgin 10-rt back on and play around poking both kernels this that and
the other way again, but seems there's some phase-of-moon factor there.

-Mike