RFR: 8210547: [Linux] Uncontrolled framerate

[Thiago Milczarek Sayao]

On Sat, 4 Oct 2025 13:38:47 GMT, Thiago Milczarek Sayao <tsayao at openjdk.org> wrote:

> As Michael Zucchi pointed out on the mailing list, the high framerate occurs because `glXSwapBuffers() `operates asynchronously. To ensure proper synchronization, you can call `glFinish() `afterward, which blocks until the buffer swap is fully completed. However, when using `glXSwapIntervalSGI`, the swap interval setting applies globally rather than per drawable. In contrast, `glXSwapIntervalEXT` provides per-drawable control, allowing finer-grained vsync behavior.
> 
> I don't know if there are scenarios when the unlimited frame rate is needed - if so we should provide a option.
> 
> See [https://wikis.khronos.org/opengl/Swap_Interval](https://wikis.khronos.org/opengl/Swap_Interval)
> 
> It also selects the correct visual for transparency which needs to be depth = 32 for X11.

I'm not sure of the solution, but it's a starting point.

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PR Comment: https://git.openjdk.org/jfx/pull/1929#issuecomment-3368309541