[Question] max_render_time adjustment setting? about labwc

[vanfanel]

I'll be there testing it once it's added, for sure.

[johanmalm]

We just use wlroots scene graph API out of the box so to speak and have not (yet) implemented max_render_time.
So we just render early in the 16ms period.

[vanfanel]

Ah! That explain the lack of framerate halving caused by the late rendering in other compositors when 2 buffers swapchain is used... Thanks! :)

[johanmalm]

Maybe we ought to add max_render_time. I looked at how sway did it and shouldn't be too much effort. Probably best done in the merge window after a release in case we get something wrong with it.

[Consolatis]

Honestly I am not sure if that is worth it. AFAIR it plays tricks by assuming the render time based on the last frames and then delays rendering up until that point. However if we now take longer to render we skip a complete frame which does sound even worse than rendering too early in the timeframe. Combine that with completely unforeseeable CPU / GPU or bus usage and latency based on whatever the user is doing. IMHO labwc should work decent in regards to performance but this might be a bit too much and is even a possible cause of skipping frames that wasn't there before. Feel free to correct me if I got the idea wrong though.

[vanfanel]

Honestly I am not sure if that is worth it. AFAIR it plays tricks by assuming the render time based on the last frames and then delays rendering up until that point. However if we now take longer to render we skip a complete frame which does sound even worse than rendering too early in the timeframe. Combine that with completely unforeseeable CPU / GPU or bus usage and latency based on whatever the user is doing. IMHO labwc should work decent in regards to performance but this might be a bit too much and is even a possible cause of skipping frames that wasn't there before. Feel free to correct me if I got the idea wrong though.

I have to agree with that. Every program I've seen where previous frame times where used to infere the next had framerate problems / hiccups.