[Intel-gfx] Time for execbuf3 ?

[Joonas Lahtinen]

Quoting Lionel Landwerlin (2019-03-19 18:39:52)
> Hi all,
> 
> There are couple of extensions coming up for our userspace drivers (anv/i965)
> where we need to add additional parameters to execbuf :
> 
>     - VK_KHR_timeline_semaphore : supplying u64 points together with syncobjs
>     [1]
>     - a non public piece of work related to performance counters [2] :
>     supplying a performance configuration ID to reconfigure the performance HW
> 
> 
> Recently some discussions on IRC also highlighted the need for better reporting
> of execbuf failure.
> We have a number of bugs where execbuf fails after a number of hours running an
> application or some random conditions and it's almost impossible to figure out
> where the problem lies.
> Having a way for i915 to report what validation the input parameters actually
> fail would more helpful than EINVAL.
> 
> Some of the virtual engine stuff could also fit in there but maybe the timeline
> is too tight for that.
> 
> We've added a i915_query mechanism that is easily extendable and after exposing
> topology, it seems to be useful for adding other types of queries (engine
> discovery, memory regions and the series in [2] also exposes performance query
> configuration data).
> 
> I would really like to see a similar mechanism for an execbuf3.
> How can we help getting started in that direction?

The direction has certainly been considered for a while already, it's
mostly a matter of gathering all the requirements to avoid execbuf4 next
year :)

So if you have any other potential requirements, now is a good time to
mention them.

Regards, Joonas

> Do people have a better idea?
> 
> Thanks,
> 
> -Lionel
> 
> [1] : https://github.com/djdeath/linux/commit/
> 8f26fca6dc41d98cb01c5758be01e382a72c84aa
> [2] : https://github.com/djdeath/linux/commit/
> 58be37aae22f7b9b31792aa13415cb5809087c10