From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754707AbcANPIk (ORCPT ); Thu, 14 Jan 2016 10:08:40 -0500 Received: from www.linutronix.de ([62.245.132.108]:57549 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754411AbcANPIh (ORCPT ); Thu, 14 Jan 2016 10:08:37 -0500 Date: Thu, 14 Jan 2016 16:07:39 +0100 (CET) From: Thomas Gleixner To: Mike Galbraith cc: Sebastian Andrzej Siewior , Clark Williams , LKML , linux-rt-users , Steven Rostedt Subject: Re: [ANNOUNCE] 4.4-rc6-rt1 In-Reply-To: <1452783422.3611.8.camel@gmail.com> Message-ID: References: <20151223225755.GA21121@linutronix.de> <20151231102441.581ce1e1@sluggy.hsv.redhat.com> <1451632781.9800.22.camel@gmail.com> <20160113175845.GK29964@linutronix.de> <20160114141744.GB17776@linutronix.de> <1452781751.3460.102.camel@gmail.com> <1452783422.3611.8.camel@gmail.com> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 14 Jan 2016, Mike Galbraith wrote: > On Thu, 2016-01-14 at 15:30 +0100, Thomas Gleixner wrote: > > On Thu, 14 Jan 2016, Mike Galbraith wrote: > > > > > On Thu, 2016-01-14 at 15:17 +0100, Sebastian Andrzej Siewior wrote: > > > > * Sebastian Andrzej Siewior | 2016-01-13 18:58:45 [+0100]: > > > > > > > > > This is due to NO_HZ as far as I can tell. My AMD A10 in idle > > mode > > > > > has > > > > > 0.7% utilisation of ksoftirqd/ with CONFIG_HZ_PERIODIC and with > > > > > CONFIG_NO_HZ_FULL it shows about 25% on all CPU threads. > > > > > > > > This should fixed it: > > > > > > > > --- a/kernel/time/timer.c > > > > +++ b/kernel/time/timer.c > > > > @@ -1453,7 +1453,7 @@ u64 get_next_timer_interrupt(unsigned long > > > > basej, u64 basem) > > > > * the base lock to check when the next timer is pending and > > > > so > > > > * we assume the next jiffy. > > > > */ > > > > - return basej; > > > > + return basem + TICK_NSEC; > > > > #endif > > > > spin_lock(&base->lock); > > > > if (base->active_timers) { > > > > > > That's what I had done to stop the screaming interrupt, but box > > still > > > behaved very badly. > > > > If you turn off CONFIG_NO_HZ_FULL and switch to NO_HZ_IDLE is it > > still bad? > > I didn't have CONFIG_NO_HZ_FULL enabled, it was CONFIG_NO_HZ_IDLE. So with the above fix it still behaves badly. Can you provide your config and a hint which workload/idle/whatever state results in bad behaviour. Thanks, tglx