RFR: 8348278: Trim InitialRAMPercentage to improve startup in default modes

[Quan Anh Mai]

On Thu, 23 Jan 2025 11:27:46 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> See bug for discussion. This is the code change, which is simple. What is not simple is deciding what the new value should be. The change would probably require CSR, which I can file after we agree on the value.
> 
> I think cutting to 0.2% of RAM size gets us into good sweet spot:
>  - On huge 1024G machine, this yields 2G initial heap
>  - On reasonably sized 128G machine, this gives 256M initial heap
>  - On smaller 1G container, this gives 2M initial heap
> 
> Additional testing:
>  - [x] Linux AArch64 server fastdebug, `all`

That's fair, although as you note here initial heap size has an additional impact compared to the min and max heap size, so having its own upper bound may be justifiable.

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PR Comment: https://git.openjdk.org/jdk/pull/23262#issuecomment-2618695156