From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: Re: kernel-rt rcuc lock contention problem Date: Tue, 3 Feb 2015 21:55:46 -0200 Message-ID: <20150203235546.GA10082@amt.cnet> References: <20150128015508.GA12233@amt.cnet> <20150128180335.GR19109@linux.vnet.ibm.com> <20150128182512.GB1259@amt.cnet> <20150128185552.GT19109@linux.vnet.ibm.com> <20150202182450.GA9526@amt.cnet> <20150202153553.70dd1a5a@gandalf.local.home> <20150202204659.GA13864@amt.cnet> <20150202155528.31bcb406@gandalf.local.home> <20150202210229.GA14624@amt.cnet> <20150203153619.6bf35329@gandalf.local.home> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "Paul E. McKenney" , Steven Rostedt , Luiz Capitulino , linux-rt-users@vger.kernel.org To: Steven Rostedt Return-path: Received: from mx1.redhat.com ([209.132.183.28]:39816 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932503AbbBCX42 (ORCPT ); Tue, 3 Feb 2015 18:56:28 -0500 Content-Disposition: inline In-Reply-To: <20150203153619.6bf35329@gandalf.local.home> Sender: linux-rt-users-owner@vger.kernel.org List-ID: On Tue, Feb 03, 2015 at 03:36:19PM -0500, Steven Rostedt wrote: > On Mon, 2 Feb 2015 19:02:29 -0200 > Marcelo Tosatti wrote: > > > I am worried about two things: > > > > 1) Something calling raise_softirq(TIMER_SOFTIRQ) and lack of > > Paul's d550e81dc0dd. > > > > The result is __run_timers checking all timer wheel "nodes" > > and updating base->timer_jiffies, latency is ruined. > > > > Even if one carefully made sure no timer is present. > > > > 2) Reliance on sched timer interrupt to raise timer softirq > > in case of pending irq work (your patch) AND no_hz_full. > > > > > Isolation is the *only* way to make that work. > > > > Fine. Please see item 1) above. > > > > So basically you are saying we just need: d550e81dc0dd ? For 1), the 4 patches he mentioned, please. For 2), it was just a hypothesis (perhaps fuelled by the fact the my test box crashes with nohz_full= and isolated cpus).