[Mesa-dev] [PATCH 0/3] vulkan: Define new VK_MESA_query_timestamp extension [v3]

[Keith Packard]

Jason Ekstrand <jason at jlekstrand.net> writes:

> I haven't thought through this comment all that hard but would it make 
> sense to have three timestamps, CPU, GPU, CPU so that you have error bars 
> on the GPU timestamp?  At the very least, two timestamps would be better 
> than one so that, when we pull it into the kernel, it can provide something 
> more accurate than userspace trying to grab a snapshot.

I've updated the extension to provide both device and surface
timestamps. The supplied implementation doesn't attempt to do anything
fancy to synchronize them, but it could if we like. Of course, what we
should do is provide a generic DRM ioctl which provides both of these
values directly from the kernel in one shot so they can be more
closely synchronized.

-keith