RFR: 8322484: 22-b26 Regression in J2dBench-bimg_misc-G1 (and more) on Windows-x64 and macOS-x64

[Thomas Schatzl]

Hi all,

  please review this improvement to managing region pin counts in g1.

Some applications do millions of `Get/ReleasePrimitiveArrayCritical` operations per second, in particular some of the j2dbench benchmarks (e.g. vimg_copyarea 10M/s), on some platforms. Every pin/unpin results in an atomic operation that is the cause for these slowdown. 

Only Windows seems to be significantly affected.

This suggested change implements a per-region thread local cache storing the current pin/unpin refcount difference, writing it back only when a thread pins/unpin an object in a different region.

For these benchmarks this often reduces the amount of atomic operations to none, or a few handful; the worst improvement I have seen is that effective atomic operations were reduced to 1/10th. Overall all the j2dbench benchmark scores improve.

There is a remaining issue with the `vimg_shapes_gradient` J2dbench subbenchmark: comparing the original results (before integration of region pinning) with latest jdk23 results, there is a regression of about 5%; this is caused by the backout of a bad compiler change (https://bugs.openjdk.org/browse/JDK-8322985). This will be fixed by its redo CR https://bugs.openjdk.org/browse/JDK-8323116.

Testing: tier1-3, j2dbench, dacapo, specj*, renaissance benchmarks

Thanks,
  Thomas

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Commit messages:
 - refactoring
 - initial version

Changes: https://git.openjdk.org/jdk/pull/17552/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17552&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8322484
  Stats: 211 lines in 13 files changed: 189 ins; 3 del; 19 mod
  Patch: https://git.openjdk.org/jdk/pull/17552.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17552/head:pull/17552

PR: https://git.openjdk.org/jdk/pull/17552