From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751107AbcFNKnm (ORCPT ); Tue, 14 Jun 2016 06:43:42 -0400 Received: from foss.arm.com ([217.140.101.70]:57843 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750703AbcFNKnl (ORCPT ); Tue, 14 Jun 2016 06:43:41 -0400 Date: Tue, 14 Jun 2016 11:43:39 +0100 From: Juri Lelli To: Peter Zijlstra Cc: mingo@kernel.org, tglx@linutronix.de, rostedt@goodmis.org, xlpang@redhat.com, linux-kernel@vger.kernel.org, mathieu.desnoyers@efficios.com, jdesfossez@efficios.com, bristot@redhat.com, Ingo Molnar Subject: Re: [RFC][PATCH 3/8] sched/deadline/rtmutex: Dont miss the dl_runtime/dl_period update Message-ID: <20160614104339.GG5981@e106622-lin> References: <20160607195635.710022345@infradead.org> <20160607200215.788266764@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160607200215.788266764@infradead.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 07/06/16 21:56, Peter Zijlstra wrote: > From: Xunlei Pang > > Currently dl tasks will actually return at the very beginning > of rt_mutex_adjust_prio_chain() in !detect_deadlock cases: > > if (waiter->prio == task->prio) { > if (!detect_deadlock) > goto out_unlock_pi; // out here > else > requeue = false; > } > > As the deadline value of blocked deadline tasks(waiters) without > changing their sched_class(thus prio doesn't change) never changes, > this seems reasonable, but it actually misses the chance of updating > rt_mutex_waiter's "dl_runtime(period)_copy" if a waiter updates its > deadline parameters(dl_runtime, dl_period) or boosted waiter changes > to !deadline class. > > Thus, force deadline task not out by adding the !dl_prio() condition. > > [peterz: I should introduce more task state comparators like > rt_mutex_waiter_less, all PI prio comparisons already have this DL > exception, except this one] > > Cc: Steven Rostedt > Cc: Ingo Molnar > Cc: Thomas Gleixner > Cc: Juri Lelli > Signed-off-by: Xunlei Pang > Signed-off-by: Peter Zijlstra (Intel) > Link: http://lkml.kernel.org/r/1460633827-345-7-git-send-email-xlpang@redhat.com > --- > kernel/locking/rtmutex.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- a/kernel/locking/rtmutex.c > +++ b/kernel/locking/rtmutex.c > @@ -488,7 +488,7 @@ static int rt_mutex_adjust_prio_chain(st > * enabled we continue, but stop the requeueing in the chain > * walk. > */ > - if (waiter->prio == task->prio) { > + if (waiter->prio == task->prio && !dl_task(task)) { Right. Do we want a rt_mutex_waiter_equal() helper? As I think the comment in the changelog was also saying? Best, - Juri