[OpenJDK 2D-Dev] RFR: 8251854 [macosx] Java forces the use of discrete GPU

[Kevin Rushforth]

Does this only apply when the MacBook is running on battery, or will 
this affect performance even when the laptop is plugged in? If the 
latter, I wonder what Apple's rationale is for including a discrete 
graphics card that isn't used most of the time.

-- Kevin


On 8/24/2020 11:27 PM, Sergey Bylokhov wrote:
> On 24.08.2020 13:35, Philip Race wrote:
>>
>> Is there any performance cost to doing this ? I'd expect so. Any 
>> estimate ?
>
> Yes, performance is affected for sure:
>
>  - SwingMark:
>    OGL_Base: 14000
>    OGL_Fix: 24000
>    Metal: 18000
>
>  - Here is a j2dbench for the common draw operations(new/old/metal):
>    http://cr.openjdk.java.net/~serb/8251854/perf/results.txt
>
>   Summary:
>   OGL_base:
>     Number of tests:  24
>     Overall average:  4.556306150323041E8
>     Best spread:      0.16% variance
>     Worst spread:     4.68% variance
>     (Basis for results comparison)
>
>   OGL_fix:
>     Number of tests:  24
>     Overall average:  1.0086929824044746E8
>     Best spread:      0.04% variance
>     Worst spread:     7.89% variance
>     Comparison to basis:
>       Best result:      83.41% of basis
>       Worst result:     15.73% of basis
>       Number of wins:   0
>       Number of ties:   0
>       Number of losses: 24
>
>   metal:
>     Number of tests:  24
>     Overall average:  8.841681616575797E7
>     Best spread:      0.08% variance
>     Worst spread:     5.64% variance
>     Comparison to basis:
>       Best result:      248.11% of basis
>       Worst result:     19.1% of basis
>       Number of wins:   8
>       Number of ties:   2
>       Number of losses: 14
> ==========================================
>
>  - Here is a j2dbench for the common draw operations(newOGL vs metal 
> only):
> http://cr.openjdk.java.net/~serb/8251854/perf/newOGL_vs_Metal.txt
>     Summary:
>   OGL_fix:
>     Number of tests:  24
>     Overall average:  2.5871177969681844E7
>     Best spread:      0.04% variance
>     Worst spread:     7.01% variance
>     (Basis for results comparison)
>
>   metal:
>     Number of tests:  24
>     Overall average:  2.1896134898150157E7
>     Best spread:      0.04% variance
>     Worst spread:     1.98% variance
>     Comparison to basis:
>       Best result:      488.31% of basis
>       Worst result:     30.77% of basis
>       Number of wins:   14
>       Number of ties:   0
>       Number of losses: 10
>
>> And there's then no way to explicitly request the discrete card on a 
>> 15/16" MBP.
>
>   I have checked that the discrete card is enabled by the macOS:
>   - if the full screen window is set
>   - if the second monitor is connected
>   Do not know any other ways to enable it.
>
>
>> Should we release note this ?
>
> Yes, I think so.
> Note that it does not affect the bundled applications only apps 
> running via java launcher.
> But some(most?) bundled java applications use this flag already.
>
>