RFR: 8319795: Static huge pages are not used for CodeCache

[Evgeny Astigeevich]

On Thu, 9 Nov 2023 16:20:35 GMT, Thomas Stuefe <stuefe 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
>
> We should have a regression test for this...

@tstuefe Yes, removing the function makes sense to me. Without the function another regression test is needed because the one in this PR will be removed. I'll add the test.

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PR Comment: https://git.openjdk.org/jdk/pull/16582#issuecomment-1804196565