RFR: 8339573: Update CodeCacheSegmentSize and CodeEntryAlignment for ARM [v3]

[Boris Ulasevich]

On Mon, 14 Oct 2024 14:29:41 GMT, Boris Ulasevich <bulasevich at openjdk.org> wrote:

>> All runs with CodeCacheSegmentSize=64
>
> Thank you!

The public CodeCacheStress benchmark is very noisy, easily giving +-10% on subsequent runs. On longer runs, CodeEntryAlignment=16 give ~1% regression on Neoverse N1 (Graviton2 and Ampere Altra), but CodeEntryAlignment=32 is OK. My measurements:
- Graviton2 (Neoverse N1) results:
    - CodeEntryAlignment=16: 93.33 ± 0.60 us/op
    - CodeEntryAlignment=32: 92.10 ± 0.69 us/op
    - CodeEntryAlignment=64: 92.67 ± 0.62 us/op
- Ampere Altra (Neoverse N1) results:
    - CodeEntryAlignment=16: 85.50 ± 0.88 us/op
    - CodeEntryAlignment=32: 83.79 ± 0.97 us/op
    - CodeEntryAlignment=64: 84.10 ± 0.82 us/op
- Graviton4 (Neoverse V2) results:
    - CodeEntryAlignment=16: 34.60 ± 0.41 us/op
    - CodeEntryAlignment=32: 34.30 ± 0.35 us/op
    - CodeEntryAlignment=64: 34.38 ± 0.40 us/op

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PR Review Comment: https://git.openjdk.org/jdk/pull/20864#discussion_r1799621570