From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: Re: [PATCH] rcu: Eliminate softirq processing from rcutree Date: Mon, 27 Jan 2014 08:54:05 -0800 Message-ID: <20140127165405.GK9012@linux.vnet.ibm.com> References: <1387773533.5369.16.camel@marge.simpson.net> <20131224193636.GD19211@linux.vnet.ibm.com> <1387940854.5373.8.camel@marge.simpson.net> <20131225075544.GE19211@linux.vnet.ibm.com> <1387993057.5346.17.camel@marge.simpson.net> <20140117171441.GG5785@linutronix.de> <1390015514.5444.46.camel@marge.simpson.net> <20140124195014.GB29981@linutronix.de> <1390626760.3625.17.camel@marge.simpson.net> <1390799444.5425.61.camel@marge.simpson.net> Reply-To: paulmck@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Sebastian Andrzej Siewior , linux-rt-users@vger.kernel.org, Steven Rostedt , linux-kernel@vger.kernel.org, Thomas Gleixner To: Mike Galbraith Return-path: Content-Disposition: inline In-Reply-To: <1390799444.5425.61.camel@marge.simpson.net> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-rt-users.vger.kernel.org On Mon, Jan 27, 2014 at 06:10:44AM +0100, Mike Galbraith wrote: > On Sat, 2014-01-25 at 06:12 +0100, Mike Galbraith wrote: > > On Fri, 2014-01-24 at 20:50 +0100, Sebastian Andrzej Siewior wrote: > > > * Mike Galbraith | 2014-01-18 04:25:14 [+0100]: > > > > > > >> ># timers-do-not-raise-softirq-unconditionally.patch > > > >> ># rtmutex-use-a-trylock-for-waiter-lock-in-trylock.patch > > > >> > > > > >> >..those two out does seem to have stabilized the thing. > > > >> > > > >> timers-do-not-raise-softirq-unconditionally.patch is on its way out. > > > >> > > > >> rtmutex-use-a-trylock-for-waiter-lock-in-trylock.patch confues me. > > > >> Didn't you report once that your box deadlocks without this patch? Now > > > >> your 64way box on the other hand does not work with it? > > > > > > > >If 'do not raise' is applied, 'use a trylock' won't save you. If 'do > > > is this just an observation or you do know why it won't save me? > > > > It's an observation from beyond the grave from the 64 core box that it > > repeatedly did NOT save :) Autopsy photos below. > > > > I've built 3.12.8-rt9 with Stevens v2 "timer: Raise softirq if there's > > irq_work" to see if it'll survive. > > And it did, configured both as nohz_tick, and nohz_full_all. The irqs > are enabled warning in can_stop_full_tick() fired for nohz_full_all, but > that's it. > > For grins, I also applied Paul's v3 timer latency series while testing > nohz_full_all config. The box was heavily loaded the vast majority of > the time, but it didn't explode or do anything obviously evil. Cool! May I add your Tested-by? Thanx, Paul