RFR: 8339573: Update CodeCacheSegmentSize and CodeEntryAlignment for ARM

[Andrew Haley]

On Fri, 13 Sep 2024 16:53:42 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> @vnkozlov Many thanks!
>> Do you reproduce the regression on a public benchmark that I can also try?
>> Now I restrict CodeEntryAlignment=16 for V1 and V2 only. And I restart my performance tests.
>
>> Do you reproduce the regression on a public benchmark that I can also try?
> 
> It was our internal benchmark.

> @vnkozlov Many thanks! Do you reproduce the regression on a public benchmark that I can also try? Now I restrict CodeEntryAlignment=16 for V1 and V2 only. And I restart my performance tests.

I think that's the wrong way around. The `default` should be 64, maybe with smaller settings where we know it helps performance.  It makes little sense to set the default CodeEntryAlignment to less than the icache line size. except in severely constrained environments.

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PR Comment: https://git.openjdk.org/jdk/pull/20864#issuecomment-2350914179