<AWT Dev> [jdk17] RFR: 8266079: Lanai: AlphaComposite shows differences on Metal compared to OpenGL

Jayathirth D V jdv at openjdk.java.net
Thu Jun 17 09:44:14 UTC 2021

On Thu, 17 Jun 2021 07:06:24 GMT, Jayathirth D V <jdv at openjdk.org> wrote:

>> Implemented blit via compute kernel
> src/java.desktop/macosx/native/libawt_lwawt/java2d/metal/MTLLayer.m line 136:
>> 134:         NSUInteger w = computePipelineState.threadExecutionWidth;
>> 135: 
>> 136:         // Workaround for some OS/device bug reporting incorrect maxTotalThreadsPerThreadgroup
> @avu Do we know in which hardware we have this issue? Also do we have any reference to Apple bug?
> Also if we use thread group as 1 what is the performance impact in such hardware?

Forced maxTotalThreadsPerThreadgroup to 1 and tested in Intel SoC 2015 Macbook Pro, as expected i see almost ~50% reduction in FPS numbers in many use cases in RenderPerfTest. This final blit hits common operation and we would be able to make better decision whether this performance reduction is okay or not based on hardware in which we are seeing Apple bug.


PR: https://git.openjdk.java.net/jdk17/pull/62

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