Re: [Xenomai-help] RT OS Selection advice for parallel processing

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

Jan Kiszka wrote:
> On 2011-02-03 12:27, Gilles Chanteperdrix wrote:
>> Jan Kiszka wrote:
>>> On 2011-02-03 12:04, Gilles Chanteperdrix wrote:
>>>> Jan Kiszka wrote:
>>>>> [ And, personally, I don't trust the NVIDIA driver a lot. But that might
>>>>> be influenced by the fact that latest versions lock up my notebook
>>>>> regularly after resume and that I filed another obvious locking issue of
>>>>> the compilable driver stub around mmap_sem without any response from the
>>>>> vendor. ]
>>>> Some colleague of mine is using the NVIDIA driver (through the opengl
>>>> mapping, not CUDA/VDPAU, whatever) on high-end NVIDIA boards in a non RT
>>>> situation. he definitely observed some huge latencies not due to
>>>> scheduling issues, when uploading textures to the GPU. We are talking
>>>> tens of milliseconds here.
>>> Ugh, tens of milliseconds is heavy, more than I would expect from
>>> wbinvd. OTOH, uploading textures may involve mapping the RAM that
>>> contains them for the GPU. To exclude that as source, he could try
>>> instrumenting CACHE_FLUSH() (in nv-linux.h).
>> No, it really looks like a bug in the blob. Of course the 40ms is a spot
>> from time to time, usually, the upload is really fast.
> 
> Unless it's a stall on the PCI bus, the blob should leaves some traces
> in ftrace.

I am talking about the kernel-space blob. ftrance does just show that
the ioctl has been submitted.



-- 
					    Gilles.