RFR: 8364114: Test TestHugePageDecisionsAtVMStartup.java#LP_enabled fails when no free hugepage

[SendaoYan]

Hi all,

The test runtime/os/TestHugePageDecisionsAtVMStartup.java#LP_enabled will fails when there is no free hugepases.
The /proc/meminfo and /sys/kernel/mm/hugepages/hugepages-*/free_hugepages says there is no free hugepage, and the JVM output also say there is available large page.


> cat /proc/meminfo | grep -i HugePages
AnonHugePages:         0 kB
ShmemHugePages:        0 kB
FileHugePages:         0 kB
HugePages_Total:       2
HugePages_Free:        0
HugePages_Rsvd:        0
HugePages_Surp:        2
Hugepagesize:       2048 kB

> ( set -x ; cat /sys/kernel/mm/hugepages/hugepages-*/free_hugepages )
+ cat /sys/kernel/mm/hugepages/hugepages-1048576kB/free_hugepages /sys/kernel/mm/hugepages/hugepages-2048kB/free_hugepages
0
0

JVM output snippet from java -XX:+UseLargePages -Xlog:pagesize -version
[0.001s][info][pagesize] Large page size (2M) failed sanity check, checking if smaller large page sizes are usable
[0.001s][warning][pagesize] UseLargePages disabled, no large pages configured and available on the system.


The JVM can not use large page when there is no available large, it's not a JVM bug. So I think it's not suitable to report test failure, but report SkippedException.

Change has been verified locally, test report SkippedException on the system without free hugepage, the test passes on the system with free hugepage. Test-fix only, risk is low.

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Commit messages:
 - 8364114: Test TestHugePageDecisionsAtVMStartup.java#LP_enabled fails when no free hugepage

Changes: https://git.openjdk.org/jdk/pull/26480/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26480&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8364114
  Stats: 23 lines in 2 files changed: 22 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/26480.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26480/head:pull/26480

PR: https://git.openjdk.org/jdk/pull/26480