From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sebastian Andrzej Siewior Subject: Re: [PATCH RT 4/6] rt/locking: Reenable migration accross schedule Date: Fri, 8 Apr 2016 12:30:23 +0200 Message-ID: <5707883F.4080302@linutronix.de> References: <1455318168-7125-1-git-send-email-bigeasy@linutronix.de> <1455318168-7125-4-git-send-email-bigeasy@linutronix.de> <1458463425.3908.5.camel@gmail.com> <1458814024.23732.35.camel@gmail.com> <1459405903.14336.64.camel@gmail.com> <20160401211105.GE29603@linutronix.de> <1459566735.3779.36.camel@gmail.com> <57068F28.8010409@linutronix.de> <1460055880.4435.61.camel@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Cc: Thomas Gleixner , linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org, Steven Rostedt , Peter Zijlstra To: Mike Galbraith Return-path: In-Reply-To: <1460055880.4435.61.camel@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-rt-users.vger.kernel.org On 04/07/2016 09:04 PM, Mike Galbraith wrote: >> just to be clear: The patch I attached did _not_ work for you. > > Sorry, I didn't test. Marathon stress test session convinced me that > the lock added by -rt absolutely had to die. Okay. And the patch did that. I removed the lock. >>> If that lock dies, we can unpin when entering lock slow path and pin >>> again post acquisition with no ABBA worries as well, and not only does >>> existing hotplug work heaping truckloads better, -rt can perhaps help >>> spot trouble as the rewrite proceeds. >>> >>> Current state is more broken than ever.. if that's possible. >> >> And the two patches you attached here did? > > I've killed way too many NOPREEMPT kernels to make any rash -rt claims. > What I can tell you is that my 64 core DL980 running 4.6-rc2-rt13 plus > the two posted patches survived for ~20 hours before I had to break it > off because I needed the box. > > These two haven't been through _as_ much pounding as the two targeted > bandaids I showed have, but have been through quite a bit. Other folks > beating the living crap outta their boxen too would not be a bad idea. I see. So what I don't like are all the exceptions you have: one for RCU and one kernfs. There might come more in the future. So what I aim is the removal of the lock. > > -Mike > Sebastian