JDK-8210547[linux] frame pacing etc.

[Michael Zucchi]

On 4/10/25 01:20, Thiago Milczarek Sayão wrote:
> Just out of curiosity, I compiled the EGL version. Here:
> https://github.com/tsayao/jfx/releases/tag/test-egl
>
> It does seem to have a difference in frame rate.
>

That's a lot better, it's basically the same as if I remove the 
makeCurrent() from ES2Pipeline.present and I presume how it behaves on 
other systems.  I still think it's throttling in the wrong place and the 
GlassTimer is terrible,  but at least it's throttling.  I'll probably 
try 25 with the latest mesa and if i still see it file a bug with them.

Over the last few days I did a lot of analysis with a more complex 
application - one that calculates an image sequence via OpenCL and 
displays it in JavaFX.  The OpenCL takes from about 3 to 15ms to 
complete depending on the scene.  I've attached some inter-pulse timing 
plots which are a bit more interesting than the previous ones.

There's JavaFX 25, my patches (Z), and the with your EGL build (I also 
tested with the makeCurrent() change since it's a single window, and it 
matches the EGL one).

 From left to right, top to bottom:

 1. Transition with no frame-rate, asynchronous rendering that drops
    work if a new request comes in while it's busy.
 2. Transition with 60f/s desired frame rate, asynchronous rendering as 1.
 3. Transition with no frame-rate, synchronous rendering on the
    animation thread.
 4. Transition with 60/s desired frame rate, synchronous rendering as 3.


Setting a desired frame rate on the Transition results in considerable 
microstutter even with the egl version.  Not setting a desired frame 
rate - visually it's ok but there is still more frame pacing variation 
than calling glFinish() after all scenes have been drawn and with a more 
accurate timer.

I want to try to do some latency testing if I can work out a reasonable 
way to do it.

For what it's worth i've also attached current patch-in-progress that 
includes a more accurate if rather simple timer.

Regards,
  !Z


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