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

[Sergey Bylokhov]

On 25.08.2020 05:43, Kevin Rushforth wrote:
> 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.

It is applied if the "automatic graphics switching" is enabled, if the user disables
this feature for the "power adapter" mode, then the discrete graphics will be always used.

I guess by default they try to "maximize battery life":
https://support.apple.com/en-us/HT202043

> 
> -- 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.
>>
>>
> 


-- 
Best regards, Sergey.