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From: Mario Kleiner <mario.kleiner@tuebingen.mpg.de>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Hurley <peter@hurleysoftware.com>,
	"Luis Claudio R. Goncalves" <lclaudio@uudg.org>,
	linux-rt-users <linux-rt-users@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Clark Williams <williams@redhat.com>,
	Dave Airlie <airlied@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Mario Kleiner <mario.kleiner@tuebingen.mpg.de>
Subject: Re: BUG: sleeping function called from invalid context on 3.10.10-rt7
Date: Wed, 11 Sep 2013 21:07:10 +0200	[thread overview]
Message-ID: <5230BF5E.9000207@tuebingen.mpg.de> (raw)
In-Reply-To: <20130911143557.14c1fe6a@gandalf.local.home>



On 11.09.13 20:35, Steven Rostedt wrote:
> On Wed, 11 Sep 2013 20:29:07 +0200
> Mario Kleiner <mario.kleiner@tuebingen.mpg.de> wrote:
>
>> That said, maybe preempt_disable is no longer the optimal choice there
>> and there's some better way to achieve good protection against
>> interruptions of that bit of code? My knowledge here is a bit rusty, and
>> the intel kms drivers and rt stuff has changed quite a bit.
>
> If you set your code to a higher priority than other tasks (and
> interrupts) than it wont be preempted there. Unless of course it blocks
> on a lock, but even then, priority inheritance will take place and it
> still should be rather quick. (unless the holder of the lock is doing
> that strange polling).
>
> -- Steve
>

Right, on a rt kernel. But that creates the problem of not very computer 
savvy users (psychologists and biologists mostly) somehow having to 
choose proper priorities for gpu interrupt threads and for the 
x-server/wayland/..., and not much protection on a non-rt kernel?

preempt_disable() a few years ago looked like a good "plug and play" 
default solution, because the ->get_crtc_scanoutpos() function was 
supposed to have a very low and bounded execution time. At the time we 
wrote the patches for intel/radeon/nouveau, that was the case. Typical 
execution time (= preempt off time) was like 1-4 usecs, even on very low 
end hardware.

Seems that at least intel's kms driver does a lot of things now, which 
can sleep and spin inside that section? I tried to follow the posted 
stack trace, but got lost somewhere around the i915_read32 code and 
power management stuff...

-mario

  reply	other threads:[~2013-09-11 19:07 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-09-11 10:28 BUG: sleeping function called from invalid context on 3.10.10-rt7 Luis Claudio R. Goncalves
2013-09-11 13:26 ` Steven Rostedt
2013-09-11 15:16   ` Peter Hurley
2013-09-11 15:38     ` Steven Rostedt
2013-09-11 19:31       ` Peter Hurley
2013-09-17 19:50         ` Peter Hurley
2013-09-17 20:55           ` Daniel Vetter
2013-09-18 16:52             ` Peter Hurley
2013-09-18 17:03               ` Daniel Vetter
2013-09-18 17:03               ` Ville Syrjälä
2013-09-20 22:07             ` Mario Kleiner
2013-09-23  8:38               ` [Intel-gfx] " Ville Syrjälä
2013-09-25  4:32                 ` Mario Kleiner
2013-09-25  7:49                   ` [Intel-gfx] " Ville Syrjälä
2013-09-25 14:18                     ` Steven Rostedt
2013-09-26 16:43                     ` Mario Kleiner
2013-09-25 13:52                   ` Steven Rostedt
2013-09-25 14:13                   ` Steven Rostedt
2013-09-26 16:16                     ` Mario Kleiner
2013-10-11 10:18                       ` Sebastian Andrzej Siewior
2013-10-11 12:37                         ` Steven Rostedt
2013-10-11 13:30                           ` Sebastian Andrzej Siewior
2013-10-11 13:49                             ` Mario Kleiner
2013-10-11 14:38                             ` Steven Rostedt
2013-09-25 14:07               ` Steven Rostedt
2013-09-11 18:29     ` Mario Kleiner
2013-09-11 18:35       ` Steven Rostedt
2013-09-11 19:07         ` Mario Kleiner [this message]
2013-09-11 19:19           ` Steven Rostedt
2013-09-11 20:23             ` Mario Kleiner
2013-10-11 14:19 ` Sebastian Andrzej Siewior
2013-10-11 14:45   ` Luis Claudio R. Goncalves

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