RFR: 8319795: Static huge pages are not used for CodeCache [v6]

[Thomas Stuefe]

On Tue, 28 Nov 2023 23:24:19 GMT, Evgeny Astigeevich <eastigeevich at openjdk.org> wrote:

>> This is a fix of a regression introduced by [JDK-8261894](https://bugs.openjdk.org/browse/JDK-8261894).
>> After JDK-8261894, `os::can_execute_large_page_memory()` returns `true` only if `UseTransparentHugePages` is true. As CodeCache uses `os::can_execute_large_page_memory()` when it detects a page size, CodeCache cannot use static huge pages (`UseTransparentHugePages` is `false`) anymore after the change.
>> Before JDK-8261894, `os::can_execute_large_page_memory()` returned `true`  when either `UseTransparentHugePages` or `UseHugeTLBFS` was true.
>> 
>> After JDK-8261894, `XX:+UseLargePages XX:-UseTransparentHugePages` means to use static huge pages: aka `UseHugeTLBFS` is `true`. If `UseLargePages` is not set to `true` via the option, it will be set to `true` if `UseTransparentHugePages` is `true`.
>> 
>> `os::can_execute_large_page_memory()` is modified to return `UseLargePages`. A regression gtest  is added.
>> 
>> Tested fastdebug and release builds:
>> - [x] tier1
>> - [x] gtest
>> - [x] test/hotspot/jtreg/gtest/LargePageGtests.java
>
> Evgeny Astigeevich has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix code heap initial sizes to be multiple of rs.alignment()

Sorry, no time to look at this in depth atm. This is suddenly a large patch, not sure why. I'd suggest to keep refactoring for a different RFE.

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PR Comment: https://git.openjdk.org/jdk/pull/16582#issuecomment-1832726879