Thanks for the answers! I have found the root cause in my code: I realized that GtkGlArea render calls are not called automatically for each screen refresh, and the observed ~40Hz was coming from my program (a timer I already forgot triggered redraw with this rate).
What is the common way to request rendering for every screen refresh? Now I have added a gtk_widget_queue_draw() into my render callback itself; is this the best technique? With this, I got ~59.2Hz, what seems ok, but also indicates that I have significant frame drops (>1%), even with reniced -19 priority process... As I mentioned, my rendering is very fast, <1ms. It would be desirable if I could get info about the current frame counter, i.e., similar to one in page_flip_handler's sequence in DRM world, because I would like to use some optimizations based on that. Is it possible to get this info? Thanks, Ferenc On Sat, Feb 4, 2017 at 10:04 AM, Tarnyko <tarn...@tarnyko.net> wrote: > Ferenc, > Your program's rendering is slower than the monitor nominal refresh rate, > which is perfectly possible if your scenes are heavy. > Please note that it could also render _faster_ (FPS higher than refresh > rate). > Scenes FPS are not directly tied to your monitor, unless you enable what > we call "VSync" : i.e. your FPS are higher than 60, but you > programmatically force it down to 60. The benefit is avoiding what we call > "tearing", which is a display artifact that your eye could notice. > Regards, > Tarnyko > Ferenc Engárd writes: > >> Hi, >> I have a strange issue with GtkGlArea under linux: it seems my program >> runs >> with a different fps than the monitor's refresh rate. (The rendering >> itself >> is fast, faster than 1ms.) >> I use a 60Hz monitor mode, and the rendering fps is around 39.5Hz. I >> verified my monitor refresh rate with xrandr, and even with another -- >> X11-EGL based -- program; it is really 60Hz. >> I also measured the time interval between two render calls, and the min >> and >> max is around 22ms and 28ms, so it seems that I even do not drop a frame. >> I do not set anything special in GtkGlArea or opengl (glSwapInterval or >> so)... >> Did you encounter with such an issue? Any idea what can be the problem? >> Ubuntu 16.04, unity, gtk+ 3.18.9 >> Thanks, >> Ferenc >> >
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