JFR: YoungGenerationConfiguration event

[tajila]

The YoungGenerationConfig event contains the following fields:

minSize - j9gc_get_minimum_young_generation_size()
maxSize - j9gc_get_maximum_young_generation_size()
newRatio - New ratio=N, where Young gen = (1/(1 + N)) * total Heap size

//total heap size - j9gc_get_maximum_heap_size()

The GCHeapConfig event only needs to be written in the initial chunk. In JFRChunkWriter::writeJFRChunk this event can be added along the other 1 time events if (0 == _vm->jfrState.jfrChunkCount) {.

Note, not all J9 GC policies have a nursery/tenure (AKA young/old generation), in these cases the answer for all fields is zero.

[tajila]

@adpopescu Please take a look at this issue

[adpopescu]

@tajila I assume where it says GCHeapConfig in the description, it's meant to be YoungGenerationConfig?

[tajila]

@tajila I assume where it says GCHeapConfig in the description, it's meant to be YoungGenerationConfig?

Yes