RFR: JDK-8256155: os::Linux Populate all large_page_sizes, select smallest page size in reserve_memory_special_huge_tlbfs* [v4]
Marcus G K Williams
github.com+168222+mgkwill at openjdk.java.net
Fri Dec 4 00:01:02 UTC 2020
On Thu, 3 Dec 2020 23:48:15 GMT, Marcus G K Williams <github.com+168222+mgkwill at openjdk.org> wrote:
>> When using LargePageSizeInBytes=1G, os::Linux::reserve_memory_special_huge_tlbfs* cannot select large pages smaller than 1G. Code heap usually uses less than 1G, so currently the code precludes code heap from using
>> Large pages in this circumstance and when os::Linux::reserve_memory_special_huge_tlbfs* is called page sizes fall back to Linux::page_size() (usually 4k).
>>
>> This change allows the above use case by populating all large_page_sizes present in /sys/kernel/mm/hugepages in _page_sizes upon calling os::Linux::setup_large_page_size().
>>
>> In os::Linux::reserve_memory_special_huge_tlbfs* we then select the largest large page size available in _page_sizes that is smaller than bytes being reserved.
>
> Marcus G K Williams has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains seven additional commits since the last revision:
>
> - Adress Comments, Rework changes for PagesizeSet
>
> Signed-off-by: Marcus G K Williams <marcus.williams at intel.com>
> - JDK-8257588: Make os::_page_sizes a bitmask #1522
> - Merge branch 'master' into update_hlp
> - Merge branch 'update_hlp' of github.com:mgkwill/jdk into update_hlp
> - Add 2M LargePages to _page_sizes
>
> Use 2m pages for large page requests
> less than 1g on linux when 1G are default
> pages
>
> - Add os::Linux::large_page_size_2m() that
> returns 2m as size
> - Add os::Linux::select_large_page_size() to return
> correct large page size for size_t bytes
> - Add 2m size to _page_sizes array
> - Update reserve_memory_special methods
> to set/use large_page_size based on bytes reserved
> - Update large page not reserved warnings
> to include large_page_size attempted
> - Update TestLargePageUseForAuxMemory.java
> to expect 2m large pages in some instances
>
> Signed-off-by: Marcus G K Williams <marcus.williams at intel.com>
> - Merge remote-tracking branch 'upstream/master' into update_hlp
> - Add 2M LargePages to _page_sizes
>
> Use 2m pages for large page requests
> less than 1g on linux when 1G are default
> pages
>
> - Add os::Linux::large_page_size_2m() that
> returns 2m as size
> - Add os::Linux::select_large_page_size() to return
> correct large page size for size_t bytes
> - Add 2m size to _page_sizes array
> - Update reserve_memory_special methods
> to set/use large_page_size based on bytes reserved
> - Update large page not reserved warnings
> to include large_page_size attempted
> - Update TestLargePageUseForAuxMemory.java
> to expect 2m large pages in some instances
>
> Signed-off-by: Marcus G K Williams <marcus.williams at intel.com>
src/hotspot/os/linux/os_linux.cpp line 3900:
> 3898: err); \
> 3899: } while (0)
> 3900:
Remove this remnant of UseSHM changes.
-------------
PR: https://git.openjdk.java.net/jdk/pull/1153
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