[jdk17u-dev] RFR: 8293503: gc/metaspace/TestMetaspacePerfCounters.java#Epsilon-64 failed assertGreaterThanOrEqual: expected MMM >= NNN [v2]

[SendaoYan]

> Hi,
>  Backport of JDK-[8293503](https://bugs.openjdk.org/browse/JDK-8293503), to fix the [intermittent failure](https://github.com/openjdk-bots/jdk17u-dev/actions/runs/8841821807/job/24280514750) of TestMetaspacePerfCounters.java.
>   This PR add a proper barrier inbetween two measurements. Only change the testcase, the change has been verify on below binary:
> 
> - [x] linux x64 release
> - [x] linux x64 fastdebug
> - [x] linux x86 release
> - [x] linux x86 fastdebug

SendaoYan 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 two additional commits since the last revision:

 - Merge branch 'openjdk:master' into jbs8293503
 - Backport 04d7b7d5747d887e12797df8ca3f7608d73d41ff

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

Changes:
  - all: https://git.openjdk.org/jdk17u-dev/pull/2431/files
  - new: https://git.openjdk.org/jdk17u-dev/pull/2431/files/8cce5c8d..fe16685c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2431&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2431&range=00-01

  Stats: 2422 lines in 75 files changed: 1100 ins; 1152 del; 170 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2431.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2431/head:pull/2431

PR: https://git.openjdk.org/jdk17u-dev/pull/2431