RFR: 8256155: Allow multiple large page sizes to be used on Linux [v29]

[Marcus G K Williams]

On Mon, 26 Apr 2021 08:31:29 GMT, Stefan Johansson <sjohanss at openjdk.org> wrote:

>> Marcus G K Williams has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 48 commits:
>> 
>>  - Set LargePageSizeInBytes to largepage upper limit
>>    
>>    Signed-off-by: Marcus G K Williams <marcus.williams at intel.com>
>>  - Merge branch 'master' into update_hlp
>>  - Fix merge
>>    
>>    Signed-off-by: Marcus G K Williams <marcus.williams at intel.com>
>>  - Merge branch 'master' into update_hlp
>>  - Merge branch 'master' into update_hlp
>>  - Rebase on pull/3073
>>    
>>    Signed-off-by: Marcus G K Williams <marcus.williams at intel.com>
>>  - Merge branch 'pull/3073' into update_hlp
>>  - Thomas review.
>>    
>>    Changed commit_memory_special to return bool to signal if the request succeeded or not.
>>  - Self review.
>>    
>>    Update helper name to better match commit_memory_special().
>>  - Marcus review.
>>    
>>    Updated comments.
>>  - ... and 38 more: https://git.openjdk.java.net/jdk/compare/5aab1609...6f063309
>
> src/hotspot/os/linux/os_linux.cpp line 3737:
> 
>> 3735:   // Populate large page sizes to _page_sizes. Add pages that
>> 3736:   // are less than or equal to LargePageSizeInBytes, except when LargePageSizeInBytes=0
>> 3737:   // or FLAG_IS_DEFAULT(LargePageSizeInBytes), add all sizes
> 
> What we currently have in the CSR is to use the default large page size as the max if `LargePageSizeInBytes`is not set. If we first check if `LargePageSizeInBytes` have been set and update `_large_page_size` accordingly above (see comment below). I think this comment should say something like:
> 
> Suggestion:
> 
>   // Populate _page_sizes with large page sizes less than or equal to
>   // _large_page_size.

+1

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PR: https://git.openjdk.java.net/jdk/pull/1153