Re: [Xenomai] NVIDIA Drivers w/ Xenomai

From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
To: Lennart Sorensen <lsorense@csclub.uwaterloo.ca>
Cc: xenomai@xenomai.org
Subject: Re: [Xenomai] NVIDIA Drivers w/ Xenomai
Date: Tue, 22 Dec 2015 08:30:37 +0100	[thread overview]
Message-ID: <20151222073037.GC29679@hermes.click-hack.org> (raw)
In-Reply-To: <20151222024304.GR25177@csclub.uwaterloo.ca>

On Mon, Dec 21, 2015 at 09:43:04PM -0500, Lennart Sorensen wrote:
> On Mon, Dec 21, 2015 at 07:22:26PM -0500, Eric Huang wrote:
> > The specific question I am trying to answer is whether it is possible (at
> > all) to install an NVIDIA driver alongside Xenomai
> > 
> > My system is the following.
> > 
> > uname -a
> > Linux robot-Z68X-UD3H-B3 3.2.21-xenomai-2.6.1 #1 SMP Thu Jul 26 11:46:23
> > EDT 2012 x86_64 x86_64 x86_64 GNU/Linux
> > 
> > xeno-config --version
> > 2.5.5.2
> 
> Wow that is really really old.
> 
> > For more details, my application is a real-time controller which needs to
> > do image processing on a GPU. The image processing code executes at 500ms
> > on a CPU and 15ms on a GPU. The image frame rate is 30hz. The control loop
> > frequency is 500hz. The control loop is the only part which needs to be
> > hard RT.
> > 
> > If I can't install and run the NVIDIA driver at all on my system I will
> > look into a solution with a separate control and perception computer.
> 
> Since xenomai uses ipipe which changes the way IRQs are handled, the
> fact you don't have source code to recompile the nvidia driver means you
> can make the nvidia driver work correctly with ipipe, so if you have the
> nvidia driver running you really have no idea if you will get real time
> or not since the nvidia driver won't be following the rules.
> 
> At least that is how I have understood the situation.

Last time I looked, NVIDIA drivers used some glue code to adapt to
the particular kernel for which they were compiled. This glue made
use of the standard macro local_irq_save/spin_lock_irqsave, etc...
So, compiling the NVIDIA driver with an I-pipe kernel worked, and so
did running Xenomai programs along side graphic applications. But
that was a long time ago. In any case, running the latency test
while your image processing program is running on the GPU should
allow you to find whether the driver is generating large latencies.

-- 
					    Gilles.
https://click-hack.org