RFR: 8256155: 2M large pages for code when LargePageSizeInBytes is set to 1G for heap [v2]

[Marcus G K Williams]

> 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>

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 one commit:

  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>

-------------

Changes: https://git.openjdk.java.net/jdk/pull/1153/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1153&range=01
  Stats: 105 lines in 3 files changed: 75 ins; 0 del; 30 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1153.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1153/head:pull/1153

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