Jerome Glisse wrote:
> On Mon, 2009-08-31 at 10:40 +0200, Thomas Hellström wrote:
>   
>> Jerome and other Radeon developers.
>>
>> You're probably aware of this, but I'd thought I'd mention it before the 
>> Radeon user-space interface is set in stone.
>>
>> There is a slight problem with the radeon bo wait idle ioctl if there 
>> are multiple threads or processes rendering to the same buffer without 
>> synchronization.
>> The ioctl effectively guarantees that all graphics commands put in the 
>> pipeline before the ioctl was called are finished, but it can never 
>> guarantee that the buffer is idle on return.
>>
>> I'm not sure this is a problem in practice, though.
>>
>> /Thomas
>>     
>
> I think we all agreed at some point that synchronization on shared
> buffer is userspace issue so it's up to sharing userspace process
> to ensure that no one is doing stuff on their back on a shared buffer.
> Right now i think the only sharing we have is btw GL process and
> X server. I haven't looked at what happen in threaded or forked
> application.
>   
Yes,
I don't think that's a problem with OpenGL at least since it requires 
the app to synchronize.
Just wanted to make sure that you were aware of the limitations,
(wait idle is really just a synchronization point).

/Thomas

> That being said i don't think we should move out of testing for 2.6.32,
> i really would like to merge read/write domain and i have an approach
> which allow to keep same userspace while allowing new userspace
> (like gallium) to use simpler approach.
>
> Jerome
>
>   




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