https://bugs.kde.org/show_bug.cgi?id=489952
--- Comment #41 from pallaswept <[email protected]> --- This is definitely vastly better, but there are still frame pacing problems. vblank intervals (in gpuvis/trace-cmd reports) are perfect within single-digit microseconds, if I run an app without vsync, and let it spin... but the same app will show constant variation in frametimes if it's vsynced, and the vblank intervals are averaging out to (I think *exactly*, it's real close!) 10us too long every time. It's definitely always too long by some amount. If the app's framerate is limited below the refresh rate, it never drops a beat. It's the same with triple buffering enabled/disabled, but mailbox doesnt seem effected. I thought that was interesting because as far as I understand it's still synced to vblank (which fails for fifo mode) , but single-buffered like immediate is (which works). I think I might be looking at a different issue and closing this one but I'm not sure yet. While I've been tracing, I'm pretty sure I caught this bug report in action: https://old.reddit.com/r/kde/comments/1og5l4c/is_kde_to_blame_for_this_weird_issue_where/ It's reported there as alt-tabbing and a permanent FPS boost, but in an isolated environment from the game (vkcube, glxgears) there are timing problems when any app starts, and then they disappear for up to a minute or two when it is minimized then raised again. It really threw a spanner in the works of my testing because everything fails until I minimize it, and then it's only reliable for a while, during which the frametimes are a flat line, and afterwards, it goes back to being all wobbly resulting from the long frames as described above. I've also come across a mangohud bug which is diverting my time from this as it's blocking my tests, (and might even be contributing to problems, unknown) but I will get it done soon. BTW, mangohud recently got an ftrace plot feature, which will be super handy for jobs like this for quick visualisation. The setup it needs is the same as gpuvis (trace-cmd-foo.sh scripts) and then in mangohud's config we just need to change the filter for nvidia eg add 'delivered': ftrace=histogram/drm_vblank_event_delivered -- You are receiving this mail because: You are watching all bug changes.
