RFR: Generation resizing

[William Kemper]

On Mon, 5 Dec 2022 11:10:05 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

>> These changes have the generational mode track the minimum mutator utilization (percentage of process time used by mutators). When it falls below a configuration percentage (GCTimeRatio), a heuristic will transfer memory capacity to whatever generation has been using more CPU time. The assumption here is that by increasing capacity, we will decrease the collection frequency and improve the MMU.
>
> src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp line 1791:
> 
>> 1789: 
>> 1790: void ShenandoahHeap::on_cycle_start(GCCause::Cause cause, ShenandoahGeneration* generation) {
>> 1791:   log_info(gc)("on_cycle_start: %s", generation->name());
> 
> What is that logging for/ what does the log message mean? I'd either improve the log message or remove the logging (or make it dev+trace) if it was only for dev purposes.

Will remove this.

> src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp line 1804:
> 
>> 1802: 
>> 1803: void ShenandoahHeap::on_cycle_end(ShenandoahGeneration* generation) {
>> 1804:   log_info(gc)("on_cycle_end: %s", generation->name());
> 
> Same here.

Will remove this.

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PR: https://git.openjdk.org/shenandoah/pull/177