From: Steven Rostedt <rostedt@goodmis.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Lai Jiangshan <laijs@cn.fujitsu.com>,
Jason Low <jason.low2@hp.com>, Brad Mouring <bmouring@ni.com>
Subject: Re: [patch V3 7/7] rtmutex: Avoid pointless requeueing in the deadlock detection chain walk
Date: Tue, 10 Jun 2014 13:47:45 -0400 [thread overview]
Message-ID: <20140610134745.668c8a4e@gandalf.local.home> (raw)
In-Reply-To: <alpine.DEB.2.10.1406101630350.31315@nanos>
On Tue, 10 Jun 2014 19:41:39 +0200 (CEST)
Thomas Gleixner <tglx@linutronix.de> wrote:
> > On the loop back around, have something like:
> >
> > if (top_waiter) {
> > if (!task_has_pi_waiters(task))
> > goto out_unlock_pi;
>
> The task has at least one pi waiter.
>
> > if (!requeue &&
> > top_waiter != task_top_pi_waiter(task)) {
> > if (!detect_deadlock)
> > goto out_unlock_pi;
> > else
> > requeue = false;
> > }
>
> Errm? if requeue is off we are in deadlock detection chainwalk
> mode. So all we care about is whether task is blocked on
> next_lock or not.
Actually that was a typo on my part. That should have been:
if (requeue &&
...
As we don't need to read the task_top_pi_waiter() again.
-- Steve
next prev parent reply other threads:[~2014-06-10 17:47 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-09 20:28 [patch V3 0/7] rtmutex: Code clarification and optimization Thomas Gleixner
2014-06-09 20:28 ` [patch V3 1/7] rtmutex: Deobfuscate chain walk Thomas Gleixner
2014-06-09 20:59 ` Steven Rostedt
2014-06-10 3:52 ` Lai Jiangshan
2014-06-10 3:21 ` Jason Low
2014-06-10 13:57 ` Brad Mouring
2014-06-09 20:28 ` [patch V3 2/7] rtmutex: Clarify the boost/deboost part Thomas Gleixner
2014-06-10 0:37 ` Steven Rostedt
2014-06-10 3:22 ` Jason Low
2014-06-10 14:04 ` Brad Mouring
2014-06-09 20:28 ` [patch V3 3/7] rtmutex: Document pi chain walk Thomas Gleixner
2014-06-10 0:45 ` Steven Rostedt
2014-06-10 3:51 ` Lai Jiangshan
2014-06-10 14:21 ` Brad Mouring
2014-06-09 20:28 ` [patch V3 4/7] rtmutex: Siplify remove_waiter() Thomas Gleixner
2014-06-10 0:53 ` Steven Rostedt
2014-06-10 3:35 ` Lai Jiangshan
2014-06-10 3:44 ` Jason Low
2014-06-10 14:10 ` Brad Mouring
2014-06-09 20:28 ` [patch V3 5/7] rtmutex: Confine deadlock logic to futex Thomas Gleixner
2014-06-10 0:59 ` Steven Rostedt
2014-06-10 4:03 ` Lai Jiangshan
2014-06-10 17:39 ` Thomas Gleixner
2014-06-09 20:28 ` [patch V3 6/7] rtmutex: Cleanup deadlock detector debug logic Thomas Gleixner
2014-06-10 1:04 ` Steven Rostedt
2014-06-10 15:09 ` Brad Mouring
2014-06-09 20:28 ` [patch V3 7/7] rtmutex: Avoid pointless requeueing in the deadlock detection chain walk Thomas Gleixner
2014-06-10 1:20 ` Steven Rostedt
2014-06-10 3:48 ` Jason Low
2014-06-10 17:41 ` Thomas Gleixner
2014-06-10 17:47 ` Steven Rostedt [this message]
2014-06-10 20:45 ` Thomas Gleixner
2014-06-10 14:57 ` Brad Mouring
2014-06-10 15:19 ` Steven Rostedt
2014-06-10 17:43 ` Thomas Gleixner
2014-06-10 17:51 ` Steven Rostedt
2014-06-10 20:46 ` Thomas Gleixner
2014-06-10 0:27 ` [patch V3 0/7] rtmutex: Code clarification and optimization Steven Rostedt
2014-06-10 0:35 ` Steven Rostedt
2014-06-10 3:00 ` Lai Jiangshan
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