From: Peter Zijlstra <peterz@infradead.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: mingo@kernel.org, tglx@linutronix.de, juri.lelli@arm.com,
xlpang@redhat.com, linux-kernel@vger.kernel.org,
mathieu.desnoyers@efficios.com, jdesfossez@efficios.com,
bristot@redhat.com, Ingo Molnar <mingo@redhat.com>
Subject: Re: [RFC][PATCH 3/8] sched/deadline/rtmutex: Dont miss the dl_runtime/dl_period update
Date: Wed, 15 Jun 2016 19:55:12 +0200 [thread overview]
Message-ID: <20160615175512.GV30921@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20160615123007.728b088c@grimm.local.home>
On Wed, Jun 15, 2016 at 12:30:07PM -0400, Steven Rostedt wrote:
> > +++ 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)) {
>
> Isn't task the owner of the lock?
No, task is blocked on something.
> What happens if the waiter is a
> deadline task?
So the test here is a shortcut to terminate the Pi chain adjust, it says
that if the waiter and task have the same priority, we're done. Further
adjustments will not make a difference.
The problem is that for deadline tasks, prio is a useless number, so
even if they match (all deadline tasks have prio -1) they might still
not actually match.
After the last patch I suppose we could do something like:
waiter->prio == task->prio && waiter->deadline == task->dl.deadline
In any case, any condition that compares just two 'prio' values is per
definition broken if DL tasks are involved.
next prev parent reply other threads:[~2016-06-15 17:55 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-07 19:56 [RFC][PATCH 0/8] PI and assorted failings Peter Zijlstra
2016-06-07 19:56 ` [RFC][PATCH 1/8] rtmutex: Deboost before waking up the top waiter Peter Zijlstra
2016-06-14 9:09 ` Juri Lelli
2016-06-14 12:54 ` Peter Zijlstra
2016-06-14 13:20 ` Juri Lelli
2016-06-14 13:59 ` Peter Zijlstra
2016-06-14 16:36 ` Davidlohr Bueso
2016-06-14 17:01 ` Juri Lelli
2016-06-14 18:22 ` Steven Rostedt
2016-06-07 19:56 ` [RFC][PATCH 2/8] sched/rtmutex/deadline: Fix a PI crash for deadline tasks Peter Zijlstra
2016-06-14 10:21 ` Juri Lelli
2016-06-14 12:30 ` Peter Zijlstra
2016-06-14 12:53 ` Xunlei Pang
2016-06-14 13:07 ` Juri Lelli
2016-06-14 16:39 ` Juri Lelli
2016-06-14 18:42 ` Steven Rostedt
2016-06-14 20:28 ` Peter Zijlstra
2016-06-15 16:14 ` Steven Rostedt
2016-06-07 19:56 ` [RFC][PATCH 3/8] sched/deadline/rtmutex: Dont miss the dl_runtime/dl_period update Peter Zijlstra
2016-06-14 10:43 ` Juri Lelli
2016-06-14 12:09 ` Peter Zijlstra
2016-06-15 16:30 ` Steven Rostedt
2016-06-15 17:55 ` Peter Zijlstra [this message]
2016-06-07 19:56 ` [RFC][PATCH 4/8] rtmutex: Remove rt_mutex_fastunlock() Peter Zijlstra
2016-06-15 16:43 ` Steven Rostedt
2016-06-07 19:56 ` [RFC][PATCH 5/8] rtmutex: Clean up Peter Zijlstra
2016-06-14 12:08 ` Juri Lelli
2016-06-14 12:32 ` Peter Zijlstra
2016-06-14 12:41 ` Juri Lelli
2016-06-07 19:56 ` [RFC][PATCH 6/8] sched/rtmutex: Refactor rt_mutex_setprio() Peter Zijlstra
2016-06-14 13:14 ` Juri Lelli
2016-06-14 14:08 ` Peter Zijlstra
2016-06-07 19:56 ` [RFC][PATCH 7/8] sched,tracing: Update trace_sched_pi_setprio() Peter Zijlstra
2016-06-07 19:56 ` [RFC][PATCH 8/8] rtmutex: Fix PI chain order integrity Peter Zijlstra
2016-06-14 17:39 ` Juri Lelli
2016-06-14 19:44 ` Peter Zijlstra
2016-06-15 7:25 ` Juri Lelli
2016-06-27 12:23 ` Peter Zijlstra
2016-06-27 12:40 ` Thomas Gleixner
2016-06-28 9:05 ` Juri Lelli
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