RFR: 8242078: G1: Improve concurrent refinement analytics and logging

[Stefan Johansson]

Thanks for a nice clean up Kim,

On 2020-04-11 00:32, Kim Barrett wrote:
>> On Apr 9, 2020, at 4:16 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
>> […]
>>> Thanks.
>>> New webrevs:
>>> full: https://cr.openjdk.java.net/~kbarrett/8242078/open.01/
Look good in general, just a few things around logging:
src/hotspot/share/gc/g1/g1Policy.cpp
---
  481   LogTarget(Debug, gc, refine, stats) log;
  482   if (log.is_enabled()) {
  483     const struct {
  484       const char* _kind;
  485       const G1ConcurrentRefineStats* _stats;
  486     } logging_stats[] = {
  487       { "Mutator", &mut_stats },
  488       { "Concurrent", &cr_stats },
  489       { "Total", &total_stats }};
  490     for (size_t i = 0; i < ARRAY_SIZE(logging_stats); ++i) {
  491       const G1ConcurrentRefineStats* istats = logging_stats[i]._stats;
  492       log.print("%s refinement: %.2fms, refined: " SIZE_FORMAT
  493                 ", precleaned: " SIZE_FORMAT ", dirtied: " 
SIZE_FORMAT,
  494                 logging_stats[i]._kind,
  495                 istats->refinement_time().seconds() * MILLIUNITS,
  496                 istats->refined_cards(),
  497                 istats->precleaned_cards(),
  498                 istats->dirtied_cards());
  499     }
  500   }

Instead of setting up this array I would prefer to split the logging 
into a separate function. Unless I'm missing something we could do 
something like:
mut_stats.log("Mutator");
cr_stats.log("Concurrent");
total_stats.log("Total");

Or if you prefer to keep the G1ConcurrentRefineStats clean, use a helper 
that take a "stats" and a "kind".
---
  509     if (log.is_enabled()) {
  510       log.print("Concurrent refinement rate: %.2f cards/ms", rate);
  511     }
  ...
  525     if (log.is_enabled()) {
  526       log.print("Generate dirty cards rate: %.2f cards/ms", 
dirtied_rate);

If doing the above change, I don't think we need a LogTarget and then 
these could just be:
log_debug(gc, refine, stats)(...)
---

Thanks,
Stefan

>>> incr: https://cr.openjdk.java.net/~kbarrett/8242078/open.01.inc/
>>> Testing: local (linux-x64) hotspot:tier1.
>>
>> Looks good.
>>
>> Thomas
> 
> Thanks.
>