Re: [Starpu-devel] Strange behaviour using GPUs

[Xavier Lacoste <xavier.lacoste@inria.fr>]

Le 26 juil. 2013 à 17:53, Samuel Thibault a écrit :

> Xavier Lacoste, le Wed 10 Jul 2013 11:43:46 +0200, a écrit :
>> I still have some things I can't explain with my traces (eg. 
>> http://img46.imageshack.us/img46/7026/ojb.png)
>> 
>> I can see a large period where nothing is done (around 50000) and a data 
>> movement performed with dates : 63306.3 - 28261 which are killing the 
>> performances.
> 
> I don't understand either. The pink color is when we are waiting for a
> cuda memory transfer to terminate, so I'd to think the issue is inside
> CUDA...
Cédric Augonnet told me that there was an issue with Cuda Driver in StarPU.
If I remember well the driver doesn't used new possibilities given by recent 
version of CUDA, somrthing about asynchronous management. I'm really not sure 
I remember it right... Does it make sense to you ? Is this still right ?
I send a mail to Cédric so that he repeats me the right keywords but he must 
be in holidays or he didn't receive my mail.

> 
>> I also had a question about fxt, how do I set the buffer size to be sure 
>> all the event will be registered without having to synchronize on disk, is 
>> there a macro, a compilation option ?
> 
> This is the trace_buffer_size field of the starpu_conf structure.
> 
> Samuel