New Vulkan vsync mode! FIFO latest ready

[netborg]

The queue is 0 in Windows, same as when using VRR with an FPS cap. It can be seen in DXGI stats as "render latency", and it stays at 0 at all times when the FPS limiter is engaged. It can also be felt, since there's no lag.

You can increase the buffer size if you want. Like 5 frames even, but it will never fill and the queue will always be 0. I'm not sure how you'd even have the buffer contain anything more then the scanout frame and the currently rendered frame even if you wanted, since the frame rate is half the refresh at most. It never hits the vsync ceiling.

If you refer to the GPU queue, of course this is 0 when capped / in the CPU limit. You still have V-Sync lag which you can fine-tune. Specifically I'd start the frame at TARGET - EXPECTED_TIME - BUFFER.

[RealNC]

If you refer to the GPU queue, of course this is 0 when capped / in the CPU limit. You still have V-Sync lag which you can fine-tune. Specifically I'd start the frame at TARGET - EXPECTED_TIME - BUFFER.

That would be the target scanline setting in SK. It will present at a specific scanout position on the screen. I usually put it in the middle, kind of a safe zone of half a screen up/down with vsync

With vsync OFF you can try putting the present in the vertical blanking to get tear-free vsync OFF, but it sometimes miss and you get a tear at the top or bottom.

Not sure there's a way on Linux to get info about display scanline position.

[netborg]

With vsync OFF you can try putting the present in the vertical blanking to get tear-free vsync OFF, but it sometimes miss and you get a tear at the top or bottom.

Not sure there's a way on Linux to get info about display scanline position.

Yeah, I really was interested in getting this supported, as this is extremely useful for ULMB, Dyac, etc.
But of course this doesn't work with Nvidia on Linux, because they don't confirm to the kernel. On AMD you could do it, there are vblank ftrace markers which you can query.

[BallisticNick]

I think for now with the lacking Nvidia support for it, scanline sync shouldn't be a focus but I think getting fifo_latest_ready supported in dxvk low latency should be a focus, as RealNC has pointed out in linux rn we don't have a good low latency - stutter-free sync mode for people who use oled and get vrr flicker or those who like to use backlight strobing.

Should require a similar implementation to the low latency vrr framepacing.
Already fifo latest ready is a big improvement over wayland's mailbox from when I was testing with overwatch despite in the docs it says it shouldn't have any improvement over mailbox without any display timing implementation but a second opinion would be appreciated.