From: Steven Rostedt <rostedt@goodmis.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Alex Shi <alex.shi@linaro.org>,
mingo@redhat.com, corbet@lwn.net,
"open list:LOCKING PRIMITIVES" <linux-kernel@vger.kernel.org>,
Sebastian Siewior <bigeasy@linutronix.de>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 2/3] rtmutex: deboost priority conditionally when rt-mutex unlock
Date: Thu, 13 Apr 2017 12:40:14 -0400 [thread overview]
Message-ID: <20170413124014.63177422@gandalf.local.home> (raw)
In-Reply-To: <20170413162113.wgtli7v5hp6ersyb@hirez.programming.kicks-ass.net>
On Thu, 13 Apr 2017 18:21:13 +0200
Peter Zijlstra <peterz@infradead.org> wrote:
> On Thu, Apr 13, 2017 at 12:09:25PM -0400, Steven Rostedt wrote:
> > On Thu, 13 Apr 2017 16:39:52 +0200
> > Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > > On Thu, Apr 13, 2017 at 10:02:53PM +0800, Alex Shi wrote:
> > > > /*
> > > > + * 'current' release this lock, so 'current' should be a higher prio
> > > > + * task than the next top waiter, unless the current prio was gotten
> > > > + * from this top waiter, iff so, we need to deboost 'current' after
> > > > + * the lock release.
> > > > + */
> > > > + if (current->prio == waiter->prio)
> > > > + deboost = true;
> > >
> > > This is wrong.
> >
> > The comment is, especially that "iff". What if current and waiter
> > happen to have the same priority? Then it too doesn't need to be
> > deboosted.
>
> The wrongness is in comparing prio and thinking it means anything.
Because of deadline scheduling?
-- Steve
next prev parent reply other threads:[~2017-04-13 16:40 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-13 14:02 [RFC PATCH 0/3] rtmutex comments update and trival fix Alex Shi
2017-04-13 14:02 ` [PATCH 1/3] rtmutex: comments update Alex Shi
2017-04-13 15:54 ` Steven Rostedt
2017-04-14 8:52 ` Alex Shi
2017-04-14 18:43 ` Steven Rostedt
2017-04-18 8:38 ` Alex Shi
2017-04-13 16:00 ` Steven Rostedt
2017-04-13 14:02 ` [PATCH 2/3] rtmutex: deboost priority conditionally when rt-mutex unlock Alex Shi
2017-04-13 14:23 ` Sebastian Siewior
2017-04-13 14:39 ` Peter Zijlstra
2017-04-13 16:09 ` Steven Rostedt
2017-04-13 16:21 ` Peter Zijlstra
2017-04-13 16:40 ` Steven Rostedt [this message]
2017-04-13 16:51 ` Peter Zijlstra
2017-04-13 14:02 ` [PATCH 3/3] rtmutex: remove unnecessary adjust prio Alex Shi
2017-04-13 16:15 ` Steven Rostedt
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