From mboxrd@z Thu Jan 1 00:00:00 1970 From: Muli Baron Subject: Re: [ANNOUNCE] 3.12.6-rt9 Date: Tue, 21 Jan 2014 08:39:10 +0200 Message-ID: <52DE160E.7080504@gmail.com> References: <20131223225017.GA8623@linutronix.de> <1387900067.5490.33.camel@marge.simpson.net> <20140117170052.GF5785@linutronix.de> <1390014929.5444.38.camel@marge.simpson.net> <20140120211736.0c97418a@gandalf.local.home> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org To: linux-rt-users@vger.kernel.org Return-path: Received: from plane.gmane.org ([80.91.229.3]:46956 "EHLO plane.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750809AbaAUGjX (ORCPT ); Tue, 21 Jan 2014 01:39:23 -0500 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1W5UzZ-0004SZ-AT for linux-rt-users@vger.kernel.org; Tue, 21 Jan 2014 07:39:21 +0100 Received: from 82.80.125.206 ([82.80.125.206]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Tue, 21 Jan 2014 07:39:21 +0100 Received: from muli.baron by 82.80.125.206 with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Tue, 21 Jan 2014 07:39:21 +0100 In-Reply-To: <20140120211736.0c97418a@gandalf.local.home> Sender: linux-rt-users-owner@vger.kernel.org List-ID: On 21/1/2014 04:17, Steven Rostedt wrote: > On Sat, 18 Jan 2014 04:15:29 +0100 > Mike Galbraith wrote: > > >>> So you also have the timers-do-not-raise-softirq-unconditionally.patch? >> > > People have been complaining that the latest 3.12-rt does not boot on > intel i7 boxes. And by reverting this patch, it boots fine. > > I happen to have a i7 box to test on, and sure enough, the latest > 3.12-rt locks up on boot and reverting the > timers-do-not-raise-softirq-unconditionally.patch, it boots fine. > > Looking into it, I made this small update, and the box boots. Seems > checking "active_timers" is not enough to skip raising softirqs. I > haven't looked at why yet, but I would like others to test this patch > too. > > I'll leave why this lets i7 boxes boot as an exercise for Thomas ;-) > > -- Steve > > Signed-off-by: Steven Rostedt > > diff --git a/kernel/timer.c b/kernel/timer.c > index 46467be..8212c10 100644 > --- a/kernel/timer.c > +++ b/kernel/timer.c > @@ -1464,13 +1464,11 @@ void run_local_timers(void) > raise_softirq(TIMER_SOFTIRQ); > return; > } > - if (!base->active_timers) > - goto out; > > /* Check whether the next pending timer has expired */ > if (time_before_eq(base->next_timer, jiffies)) > raise_softirq(TIMER_SOFTIRQ); > -out: > + > rt_spin_unlock_after_trylock_in_irq(&base->lock); > > } > -- > To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > While this might fix booting on i7 machines it kinds of defeats the original purpose of this patch, which was to let NO_HZ_FULL work properly with threaded interrupts. With the active_timers check removed the timer interrupt keeps firing even though there is only one task running on a specific processor, since it can't shut down the tick because the ksoftirqd thread keeps getting scheduled (see the previous thread "CONFIG_NO_HZ_FULL + CONFIG_PREEMPT_RT_FULL = nogo" for the full discussion). -- Muli