RFR: JDK-8256155: os::Linux Populate all large_page_sizes, select smallest page size in reserve_memory_special_huge_tlbfs* [v16]

[Thomas Stuefe]

On Wed, 24 Feb 2021 08:12:52 GMT, Thomas Stuefe <stuefe 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 25 commits:
>> 
>>  - Merge branch 'master' into pull/1153
>>  - kstefanj update
>>    
>>    Signed-off-by: Marcus G K Williams <marcus.williams at intel.com>
>>  - Merge branch 'master' into update_hlp
>>  - Merge branch 'master' into update_hlp
>>  - Remove extraneous ' from warning
>>    
>>    Signed-off-by: Marcus G K Williams <marcus.williams at intel.com>
>>  - Merge branch 'master' into update_hlp
>>  - Merge branch 'master' into update_hlp
>>  - Merge branch 'master' into update_hlp
>>  - Fix os::large_page_size() in last update
>>    
>>    Signed-off-by: Marcus G K Williams <marcus.williams at intel.com>
>>  - Ivan W. Requested Changes
>>    
>>    Removed os::Linux::select_large_page_size and
>>    use os::page_size_for_region instead
>>    
>>    Removed Linux::find_large_page_size and use
>>    register_large_page_sizes. Streamlined
>>    Linux::setup_large_page_size
>>    
>>    Signed-off-by: Marcus G K Williams <marcus.williams at intel.com>
>>  - ... and 15 more: https://git.openjdk.java.net/jdk/compare/f4cfd758...f2e44ac7
>
> src/hotspot/os/linux/os_linux.cpp line 3670:
> 
>> 3668:     // If we can't open /sys/kernel/mm/hugepages
>> 3669:     // Add _default_large_page_size to _page_sizes
>> 3670:     _page_sizes.add(_default_large_page_size);
> 
> missing return here.

But see my general remarks. I would modify this function to not change outside state at all, just to return the found page sizes in a os::PageSizes object.

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