Valve Developer Posts High Priority AMDGPU Scheduling Support

[LeJimster]

isnt exclusive to VR. Fullscreen games need to have priority rendering that screen.

This is what I was wondering.. Will all games benefit from this work? As wasn't somebody making the case recently for the lack of performance vs windows was down to the way Linux scheduler works.

Would be interested to see benchmarks if all games benefit.

[starshipeleven]

isnt exclusive to VR. Fullscreen games need to have priority rendering that screen.

Wait a sec, doesn't fullscreen imply already that there is only ONE application rendering in there?

Sure you can have overlays, but...

[agd5f]

This is what I was wondering.. Will all games benefit from this work? As wasn't somebody making the case recently for the lack of performance vs windows was down to the way Linux scheduler works.

Would be interested to see benchmarks if all games benefit.

It depends what you mean by benefit. These patches are not about providing faster performance, they about providing more predictable latency when you have multiple apps vying for the same resources. If anything, these patches may actually hurt performance slightly in these specific uses cases, but the trade off is more predictable latency for a specific app. If there is no contention for resources, nothing should change.

[agd5f]

As long as this doesn't result in more userspace code to be run as root, sounds probably fine

Well, the app that needs priority would need some sort of elevated privilege, otherwise there is nothing stopping all apps from being able to request higher priority which would defeat the purpose.

[Zan Lynx]

isnt exclusive to VR. Fullscreen games need to have priority rendering that screen.

No no no. If you make everything high priority then nothing is. VR needs high priority in order to react immediately to motion events reported by the headset. This is not for a render of the next frame but just shifting the already rendered view to match head motion.

(I'm pretty sure ... could be wrong I suppose.)

[haagch]

Well, the app that needs priority would need some sort of elevated privilege, otherwise there is nothing stopping all apps from being able to request higher priority which would defeat the purpose.

Why is this the driver's problem? If applications do that without having a good reason to need it, then the applications are misusing a feature and ought to be fixed.

[Zan Lynx]

Check this PDF from NVIDIA. This is why you need high priority GPU contexts in VR. Look for the parts on asynchronous time warp.

https://developer.nvidia.com/sites/default/files/akamai/VRWorks/VRWORKS_Technical.pdf