RFR: 8290344: Start/stop displaysync affects performance in metal rendering pipeline

[Alexey Ushakov]

On Wed, 20 Jul 2022 11:00:32 GMT, Ajit Ghaisas <aghaisas at openjdk.org> wrote:

>> Reuse displaysync thread for subsequent updates
>
> src/java.desktop/macosx/native/libawt_lwawt/java2d/metal/MTLLayer.m line 32:
> 
>> 30: #import "MTLSurfaceData.h"
>> 31: #import "JNIUtilities.h"
>> 32: #define KEEP_ALIVE_INC 4
> 
> Why only 4?
> Have you experimented with lesser or greater values?

Yes,  4 is enough to not produce extra stops for animations with relatively high frequency (20+ FPS). I've tested it on RenderPerfTest. If you have other scenarios handy I can check them too.

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PR: https://git.openjdk.org/jdk/pull/9512