RFR: 8341643: G1: Merged cards counter skewed by merge cards cache [v2]

[Thomas Schatzl]

> Hi all,
> 
>    please review this change that subtracts the dummy cards from the merge cards counter at the end of the phase to keep its value correct.
> 
> E.g. previously log output with no actual cards being merged looks as follows:
> 
>  [0.991s][debug][gc,phases ] GC(11) Remembered Sets (ms): Min: 0.03, Avg: 0.03, Max: 0.03, Diff: 0.01, Sum: 0.11, Workers: 4
> [0.991s][debug][gc,phases ] GC(11) Eager Reclaim (ms): skipped
> [0.991s][debug][gc,phases ] GC(11) Merged Inline: Min: 0, Avg: 0.0, Max: 0, Diff: 0, Sum: 0, Workers: 4
> [0.991s][debug][gc,phases ] GC(11) Merged ArrayOfCards: Min: 0, Avg: 0.0, Max: 0, Diff: 0, Sum: 0, Workers: 4
> [0.991s][debug][gc,phases ] GC(11) Merged Howl: Min: 0, Avg: 0.0, Max: 0, Diff: 0, Sum: 0, Workers: 4
> [0.991s][debug][gc,phases ] GC(11) Merged Full: Min: 0, Avg: 0.0, Max: 0, Diff: 0, Sum: 0, Workers: 4
> [0.991s][debug][gc,phases ] GC(11) Merged Howl Inline: Min: 0, Avg: 0.0, Max: 0, Diff: 0, Sum: 0, Workers: 4
> [0.991s][debug][gc,phases ] GC(11) Merged Howl ArrayOfCards: Min: 0, Avg: 0.0, Max: 0, Diff: 0, Sum: 0, Workers: 4
> [0.991s][debug][gc,phases ] GC(11) Merged Howl BitMap: Min: 0, Avg: 0.0, Max: 0, Diff: 0, Sum: 0, Workers: 4
> [0.991s][debug][gc,phases ] GC(11) Merged Howl Full: Min: 0, Avg: 0.0, Max: 0, Diff: 0, Sum: 0, Workers: 4
> [0.991s][debug][gc,phases ] GC(11) Merged Cards: Min: 8, Avg: 8.0, Max: 8, Diff: 0, Sum: 32, Workers: 4
> 
> (Note that none of the other categories have non-zero values)
> to
> 
> [0.991s][debug][gc,phases ] GC(11) Merged Cards: Min: 0, Avg: 0.0, Max: 0, Diff: 0, Sum: 0, Workers: 4
> 
> 
> For the same test (gcbasher in this case).
> 
> Testing: gha, log messages
> 
> Thanks,
>   Thomas

Thomas Schatzl has updated the pull request incrementally with one additional commit since the last revision:

  * fix documentation

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/21390/files
  - new: https://git.openjdk.org/jdk/pull/21390/files/de1277fb..b1dc6faa

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21390&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21390&range=00-01

  Stats: 3 lines in 1 file changed: 0 ins; 1 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/21390.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21390/head:pull/21390

PR: https://git.openjdk.org/jdk/pull/21390