RFR: JDK-8256155: os::Linux Populate all large_page_sizes, select smallest page size in reserve_memory_special_huge_tlbfs* [v4]

Thu Dec 3 23:48:15 UTC 2020

> 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>

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1153/files
  - new: https://git.openjdk.java.net/jdk/pull/1153/files/57e54963..0901e70e

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1153&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1153&range=02-03

  Stats: 2740 lines in 107 files changed: 1814 ins; 632 del; 294 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