RFR: Initial sizing refactor [v2]

[William Kemper]

On Wed, 21 Dec 2022 22:13:42 GMT, Y. Srinivas Ramakrishna <ysr at openjdk.org> wrote:

>> William Kemper has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Improve assertions and comments
>
> src/hotspot/share/gc/shenandoah/shenandoahMmuTracker.cpp line 222:
> 
>> 220:   log_info(gc)("Thread Usr+Sys YOUNG = %.3f, OLD = %.3f, GLOBAL = %.3f", young_time_s, old_time_s, global_time_s);
>> 221: 
>> 222:   if (abs(delta) <= transfer_threshold) {
> 
> I thought the original idea was to use the difference in MMU's for old and young as the error signal to drive the (direction of the) transfer, rather than the difference in the actual times? Am I misinterpreting what `reset_collection_time` returns? You do refer to it as `thread utilization` (akin to MMU) in the log message below.

I reasoned that the denominator in a comparison between MMU's (i.e., process time) would be the same on both sides of the comparison, so I omitted it.

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

PR: https://git.openjdk.org/shenandoah/pull/185