Mouse clicks cause performance spikes

[lshoek]

To reproduce, add this to helloworld demo update():

if (deltaTime > 0.01)
    Logger::info("%.06f", deltaTime);

Replace 0.01 for some value that's about 5-10 times of your frame average.

Clicks inside the render window in helloworld demo

• in Debug mode seems to cause 10-16ms lag spikes (eyeballed normal frame time median 0.13-0.16ms)
• in Release mode generate the same lag spikes but less often (eyeballed normal frame time median ~0.05ms)

Hardware

• RTX 5070 Ti
• AMD Ryzen 9 9900X3D

The spikes happen after clicks only and are significant enough to not be classified as jitter. I first noticed this in another project that computes a costly simulation based on GPU feedback. What's interesting is that the lag frame is always followed by a fast frame, leading to noticeable artifacts in the simulation.

I plotted what that looks like (frame index on x-axis)

[cklosters]

Personally I haven't noticed any performance issues; this might have to do with your display manager (X11 / Wayland) on Linux in combination with your graphics driver. Interesting to see if the issue persists when you switch your display manager and / or is reproducible on Windows. If the problem is local to a specific combination the issue is most likely related to the underlying windowing system. If it persists on all platform it might be related to something in NAP, but I sincerely doubt that because we receive events from SDL3. In that case it might be worth looking at their changes / release notes.

Note that you must change the video driver to 'Wayland', to avoid reverting to XWayland in a wayland session; see NAP 0.8 release notes.

[lshoek]

I'm on Ubuntu 24/Wayland. Also tried all display modes, but FIFO (Relaxed) and Mailbox make the problem worse. The Nvidia drivers have indeed been a headache to even get to recognize this card, which is almost one year old now btw :))) Currently running the 570 open driver. At the time I set it up, it was the only one that even worked. I'll try and see if I can update now.

So it seems likely that it has something to do with the driver. If anyone else is experiencing similar issues on different hardware please lmk.

[cklosters]

Thanks for testing this; if it is related to the NVidia drivers, it might be worth considering going back to X11 because support there is better; lmk if / when you benchmark this. We should be careful ruling out the problem on our end through, so I'll try and run a benchmark sometime this or next week (AMD Radeon), but wouldn't be surprised if it boils down to nvidia's lack of support for Wayland on Linux. Also; explicitly choosing wayland instead of the system default (xwayland on ubuntu 24.04) might make a difference.

[cklosters]

I haven't found the time to explicitly profile this, but I also haven't noticed any performance spikes on mouse click with the latest NAP build on Ubuntu 24.04LTS (X11 / XWayland), Windows 11 & Raspbian (X11); Ryzen 9 5900X, Radeon RX9070 XT. Extensive clicking, including touch, didn't result in any noticeable frame-drops. If you want me to continue testing this lmk, otherwise I will close this in the new year.

[lshoek]

Quick response but I found that explicitly choosing wayland before login indeed solved the performance spikes. This is interesting because I certainly recall verifying I was on wayland with echo $XDG_SESSION_TYPE before. I will also test this later on my home desktop to double check. I had the same problem there too.