From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Galbraith Subject: Re: [patch-3.18.7-rt1] sched/context-tracking: fix PREEMPT_LAZY explosions Date: Tue, 10 Mar 2015 10:35:36 +0100 Message-ID: <1425980136.3507.17.camel@gmail.com> References: <20150216111822.GA21649@linutronix.de> <1424258514.3819.39.camel@gmail.com> <20150309134535.GA13768@linutronix.de> <1425911771.30469.8.camel@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: linux-rt-users , LKML , Thomas Gleixner , rostedt@goodmis.org, John Kacur To: Sebastian Andrzej Siewior Return-path: In-Reply-To: <1425911771.30469.8.camel@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-rt-users.vger.kernel.org On Mon, 2015-03-09 at 15:36 +0100, Mike Galbraith wrote: > On Mon, 2015-03-09 at 14:45 +0100, Sebastian Andrzej Siewior wrote: > > * Mike Galbraith | 2015-02-18 12:21:54 [+0100]: > > > > >On Mon, 2015-02-16 at 12:18 +0100, Sebastian Andrzej Siewior wrote: > > > > > >> Known issues: > > >> > > >> - lazy preempt on x86_64 leads to a crash with some load. > > > > > >The below still works for me. (it doesn't make nohz_full actually work > > >in rt, but at least folks who want to tinker with it can do so) > > So your box still crashes without it? > > > > The thing is I tried to reproduce it and it does not occur anymore. > > Neither in KVM nor on real HW. > > Heh, well that's interesting, I just presumed it would still explode > because you said it would. I'll beat on it any let you know if I'm > carrying a placebo patch or not :) Yup, someone made kaboom go away. I was able to easily blow my box out of the water by running tbench + kbuild with nohz_full active. No more. nohz_full doesn't work though, due to an otherwise solo task trying to shut the tick down having just awakened ksoftirqd.. but no more kaboom. -Mike