RFR: 8316814: NMT: A separate script or Java program is needed to analyze and make useful reports ouf of JMH benchmarks outputs.

[Afshin Zafari]

It reads the benchmark report file whose path is given as command line. Then extract percentage of overhead of NMT modes for different methods used in benchmarks.
Locally tested with some sample report files.
>From an input benchmark report like this: 

# JMH version: 1.37
# VM version: JDK 22-internal, OpenJDK 64-Bit Server VM,......in...
# VM invoker:.....
# VM options: -XX:NativeMemoryTracking=detail --add-exports java.base/jdk.internal.misc=ALL-UNNAMED -Djava.library.path=...
# Blackhole mode: compiler (auto-detected, use -Djmh.blackhole.autoDetect=false to disable)
# Warmup: 2 iterations, 1 s each
# Measurement: 5 iterations, 1 s each
# Timeout: 10 min per iteration
# Threads: 1 thread, will synchronize iterations
# Benchmark mode: Average time, time/op
# Benchmark: org.openjdk.bench.vm.runtime.NMTBenchmark.NMTDetail.mixAallocateFreeMemory
# Parameters: (N = 100000, THREADS = 4)

.
.
.


Benchmark                                               (N)  (THREADS)  Mode  Cnt    Score    Error  Units
NMTBenchmark.NMTDetail.mixAallocateFreeMemory        100000          0  avgt   10   87.010 ? 10.630  ms/op
NMTBenchmark.NMTDetail.mixAallocateFreeMemory        100000          4  avgt   10    2.473 ?  0.728  ms/op
NMTBenchmark.NMTDetail.mixAllocateReallocateMemory   100000          0  avgt   10  225.054 ?  4.381  ms/op
NMTBenchmark.NMTDetail.mixAllocateReallocateMemory   100000          4  avgt   10    2.247 ?  0.599  ms/op
NMTBenchmark.NMTDetail.onlyAllocateMemory            100000          0  avgt   10  147.346 ?  8.226  ms/op
NMTBenchmark.NMTDetail.onlyAllocateMemory            100000          4  avgt   10    2.285 ?  0.611  ms/op
NMTBenchmark.NMTOff.mixAallocateFreeMemory           100000          0  avgt   10   40.405 ?  8.115  ms/op
NMTBenchmark.NMTOff.mixAallocateFreeMemory           100000          4  avgt   10    2.299 ?  0.658  ms/op
NMTBenchmark.NMTOff.mixAllocateReallocateMemory      100000          0  avgt   10  158.700 ? 10.750  ms/op
NMTBenchmark.NMTOff.mixAllocateReallocateMemory      100000          4  avgt   10    2.282 ?  0.723  ms/op
NMTBenchmark.NMTOff.onlyAllocateMemory               100000          0  avgt   10  113.949 ? 21.257  ms/op
NMTBenchmark.NMTOff.onlyAllocateMemory               100000          4  avgt   10    2.155 ?  0.682  ms/op
NMTBenchmark.NMTSummary.mixAallocateFreeMemory       100000          0  avgt   10   50.436 ?  4.576  ms/op
NMTBenchmark.NMTSummary.mixAallocateFreeMemory       100000          4  avgt   10    2.192 ?  0.737  ms/op
NMTBenchmark.NMTSummary.mixAllocateReallocateMemory  100000          0  avgt   10  170.408 ?  4.556  ms/op
NMTBenchmark.NMTSummary.mixAllocateReallocateMemory  100000          4  avgt   10    2.344 ?  0.645  ms/op
NMTBenchmark.NMTSummary.onlyAllocateMemory           100000          0  avgt   10  117.480 ?  8.846  ms/op
NMTBenchmark.NMTSummary.onlyAllocateMemory           100000          4  avgt   10    2.367 ?  0.694  ms/op


it creates summary like this:


                                  Method Threads   Off  Summary Detail
                  mixAallocateFreeMemory     0     40.41  50.44   87.01
                                                          24.83% 115.34%
                  mixAallocateFreeMemory     4      2.30   2.19    2.47
                                                          -4.65%   7.57%
             mixAllocateReallocateMemory     0    158.70 170.41  225.05
                                                           7.38%  41.81%
             mixAllocateReallocateMemory     4      2.28   2.34    2.25
                                                           2.72%  -1.53%
                      onlyAllocateMemory     0    113.95 117.48  147.35
                                                           3.10%  29.31%
                      onlyAllocateMemory     4      2.16   2.37    2.29
                                                           9.84%   6.03%

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Commit messages:
 - white spac corrected.
 - review comments applied.
 - Error values added, results shown in one line.
 - 8316814: NMT: A separate script or Java program is needed to analyze and make useful reports ouf of JMH benchmarks outputs.

Changes: https://git.openjdk.org/jdk/pull/16070/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16070&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8316814
  Stats: 152 lines in 1 file changed: 152 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/16070.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16070/head:pull/16070

PR: https://git.openjdk.org/jdk/pull/16070