RFR: 8334371: [AIX] Beginning with AIX 7.3 TL1 mmap() supports 64K memory pages [v4]

[Martin Doerr]

On Thu, 20 Jun 2024 08:04:41 GMT, Joachim Kern <jkern at openjdk.org> wrote:

>> Beginning with AIX 7.3 TL1 mmap() supports 64K memory pages. As an enhancement, during the initialization of the VM the availability of this new feature is examined. If the 64K pages are supported the VM will use mmap() with 64K pages instead of shmget()/shmat() with 64K pages due to the bad 256M alignment of shmget()/shmat().
>
> Joachim Kern has updated the pull request incrementally with one additional commit since the last revision:
> 
>   minor changes

LGTM. Only a few minor nits. Are you planning to change https://github.com/openjdk/jdk/blob/747e1e47f576b0ca3ac97d1deea87418e67ff2d1/src/hotspot/share/runtime/os.cpp#L1924 later?

src/hotspot/os/aix/os_aix.cpp line 70:

> 68: #include "services/runtimeService.hpp"
> 69: #include "signals_posix.hpp"
> 70: #include "utilities/debug.hpp"

Should be sorted alphabetically.

src/hotspot/os/aix/os_aix.cpp line 102:

> 100: // sys/mman.h defines MAP_ANON_64K beginning with AIX7.3 TL1
> 101: #ifndef MAP_ANON_64K
> 102:   #define MAP_ANON_64K  0x400

Extra whitespace.

test/hotspot/gtest/runtime/test_os_aix.cpp line 35:

> 33: // sys/mman.h defines MAP_ANON_64K beginning with AIX7.3 TL1
> 34: #ifndef MAP_ANON_64K
> 35:   #define MAP_ANON_64K  0x400

Extra whitespace.

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PR Review: https://git.openjdk.org/jdk/pull/19771#pullrequestreview-2150988765
PR Review Comment: https://git.openjdk.org/jdk/pull/19771#discussion_r1660814069
PR Review Comment: https://git.openjdk.org/jdk/pull/19771#discussion_r1660814491
PR Review Comment: https://git.openjdk.org/jdk/pull/19771#discussion_r1660829306