Partial -prof gc results (churn and time missing for some parameters)

[Bernd Eckenfels]

Hello,

if I run the following test project the results for the GC profiler are
incomplete for the parameter runs with largest bufsize. I could understand that the large objects are directly promoted, but shouldnt there be some churn anyway?

churn and count is present for smaller sizes and constantly absent for all benchmarks with 1MB buffer.


https://github.com/ecki/jmhbench-cryptospeed

>java -jar target\jmhbench-cryptospeed.jar -t 4 -wi 1 -prof gc \.MD5$
# JMH 1.9.1 (released 6 days ago)
# VM invoker: C:\Program Files\Java\jdk1.8.0_40\jre\bin\java.exe

# Run complete. Total time: 00:01:06

Benchmark                                           (bufsize)  Mode  Cnt      Score      Error   Units
HashBenchmark.MD5                                           0  avgt    3      1.245 ±    2.054   us/op
HashBenchmark.MD5:·gc.alloc.rate                            0  avgt    3   1274.045 ± 3040.383  MB/sec
HashBenchmark.MD5:·gc.alloc.rate.norm                       0  avgt    3    414.026 ±  315.179    B/op
HashBenchmark.MD5:·gc.churn.PS_Eden_Space                   0  avgt    3   1277.885 ± 2983.771  MB/sec
HashBenchmark.MD5:·gc.churn.PS_Eden_Space.norm              0  avgt    3    415.364 ±  314.255    B/op
HashBenchmark.MD5:·gc.churn.PS_Survivor_Space               0  avgt    3      0.143 ±    1.813  MB/sec
HashBenchmark.MD5:·gc.churn.PS_Survivor_Space.norm          0  avgt    3      0.047 ±    0.617    B/op
HashBenchmark.MD5:·gc.count                                 0  avgt    3     76.000             counts
HashBenchmark.MD5:·gc.time                                  0  avgt    3     90.000                 ms
...
HashBenchmark.MD5                                     1048576  avgt    3  10289.990 ± 2722.121   us/op
HashBenchmark.MD5:·gc.alloc.rate                      1048576  avgt    3      0.179 ±    0.042  MB/sec
HashBenchmark.MD5:·gc.alloc.rate.norm                 1048576  avgt    3    482.475 ±  222.011    B/op
HashBenchmark.MD5:·gc.count                           1048576  avgt    3        ? 0             counts

Gruss
Bernd