RFR: 8274178: Occupancy value in logging and JFR event is inaccurate in G1IHOPControl

[Thomas Schatzl]

Hi,

On 09.10.21 00:19, Man Cao wrote:
> Do we want to rename the wording "current occupancy" and "occupancy" in 
> logging to something else? If we keep them as 
> G1CollectedHeap::heap()->used(), it is inconsistent with the other 
> logging message in G1Policy::need_to_start_conc_mark():
> 
> bool G1Policy::need_to_start_conc_mark(const char* source, size_t 
> alloc_word_size) {
>    ...
>    size_t cur_used_bytes = _g1h->non_young_capacity_bytes();
>    ...
>    if (marking_request_bytes > marking_initiating_used_threshold) {
>      ...
>      log_debug(gc, ergo, ihop)("%s occupancy: " SIZE_FORMAT "B 
> allocation request: " SIZE_FORMAT "B threshold: " SIZE_FORMAT "B (%1.2f) 
> source: %s",
>                                result ? "Request concurrent cycle 
> initiation (occupancy higher than threshold)" : "Do not request 
> concurrent cycle initiation (still doing mixed collections)",
>                                cur_used_bytes, alloc_byte_size, 
> marking_initiating_used_threshold, (double) 
> marking_initiating_used_threshold / _g1h->capacity() * 100, source);
>    }
> }
> 
> The "occupancy" value in this message is already non_young_capacity_bytes().
> 
> Also, if we report both heap()->used() and non_young_capacity_bytes() in 
> log, which value should we use for "current_occupancy" in 
> G1NewTracer::report_basic_ihop_statistics() and 
> G1NewTracer::report_adaptive_ihop_statistics()?
> 

  just fix it elsewhere as well, as well adding the field to the JFR events.

JFR recordings are self-describing, so this should not be an issue wrt 
to backwards compatibility for future recordings.

Thanks,
   Thomas