From: Peter Zijlstra <peterz@infradead.org>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: Maarten Lankhorst <maarten.lankhorst@canonical.com>,
linux-arch@vger.kernel.org, daniel.vetter@ffwll.ch,
x86@kernel.org, linux-kernel@vger.kernel.org,
dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org,
robclark@gmail.com, tglx@linutronix.de, mingo@elte.hu,
linux-media@vger.kernel.org
Subject: Re: [PATCH v2 2/3] mutex: add support for reservation style locks, v2
Date: Thu, 04 Apr 2013 18:49:18 +0200 [thread overview]
Message-ID: <1365094158.2609.119.camel@laptop> (raw)
In-Reply-To: <20130404133123.GW2228@phenom.ffwll.local>
On Thu, 2013-04-04 at 15:31 +0200, Daniel Vetter wrote:
> We've discussed this approach of using (rt-prio, age) instead of just
> age
> to determine the the "oldness" of a task for deadlock-breaking with
> -EAGAIN. The problem is that through PI boosting or normal rt-prio
> changes
> while tasks are trying to acquire ww_mutexes you can create acyclic
> loops
> in the blocked-on graph of ww_mutexes after the fact and so cause
> deadlocks. So we've convinced ourselves that this approche doesn't
> work.
Could you pretty please draw me a picture, I'm having trouble seeing
what you mean.
AFAICT as long as you boost Y while its the lock owner things should
work out, no?
next prev parent reply other threads:[~2013-04-04 16:49 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-28 10:24 [PATCH v2 1/3] arch: make __mutex_fastpath_lock_retval return whether fastpath succeeded or not Maarten Lankhorst
2013-02-28 10:25 ` [PATCH v2 2/3] mutex: add support for reservation style locks, v2 Maarten Lankhorst
2013-04-02 10:56 ` Peter Zijlstra
2013-04-02 10:57 ` Peter Zijlstra
2013-04-02 11:00 ` Peter Zijlstra
2013-04-02 14:57 ` Maarten Lankhorst
2013-04-02 16:59 ` Peter Zijlstra
2013-04-02 17:23 ` Daniel Vetter
2013-04-02 17:30 ` Daniel Vetter
2013-04-04 12:01 ` Peter Zijlstra
2013-04-04 13:31 ` Daniel Vetter
2013-04-04 16:33 ` Peter Zijlstra
2013-04-04 16:38 ` Peter Zijlstra
2013-04-04 16:59 ` Daniel Vetter
2013-04-09 22:27 ` Steven Rostedt
2013-04-10 8:27 ` Daniel Vetter
2013-04-04 16:39 ` Peter Zijlstra
2013-04-04 16:41 ` Peter Zijlstra
2013-04-09 22:28 ` Steven Rostedt
2013-04-10 9:33 ` Daniel Vetter
2013-04-17 19:08 ` Daniel Vetter
2013-04-18 17:37 ` Ville Syrjälä
2013-04-04 16:43 ` Peter Zijlstra
2013-04-04 16:46 ` Peter Zijlstra
2013-04-04 16:49 ` Peter Zijlstra [this message]
2013-04-04 20:44 ` Daniel Vetter
2013-04-04 16:54 ` Peter Zijlstra
2013-04-04 16:56 ` Daniel Vetter
2013-04-08 10:39 ` Peter Zijlstra
2013-04-08 11:50 ` Daniel Vetter
2013-04-10 10:34 ` Daniel Vetter
2013-04-09 22:42 ` Steven Rostedt
2013-04-10 7:34 ` Peter Zijlstra
2013-04-09 22:18 ` Steven Rostedt
2013-04-02 15:56 ` Daniel Vetter
2013-04-02 11:04 ` Peter Zijlstra
2013-02-28 10:25 ` [PATCH v2 3/3] reservation: Add tests to lib/locking-selftest.c. v2 Maarten Lankhorst
2013-03-09 12:06 ` [Linaro-mm-sig] [PATCH v2 1/3] arch: make __mutex_fastpath_lock_retval return whether fastpath succeeded or not Francesco Lavra
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