RFR (M): 8227739: Merge cost predictions for scanning cards and log buffer entries

[Kim Barrett]

> On Nov 28, 2019, at 6:13 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
> 
> http://cr.openjdk.java.net/~tschatzl/8227739/webrev.1_to_2/ (diff)
> http://cr.openjdk.java.net/~tschatzl/8227739/webrev.2/ (full)
> 
> Thanks,
>  Thomas

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src/hotspot/share/gc/g1/g1HotCardCache.cpp
  74   // This does not need an atomic update. Racing threads may at most write the
  75   // same value.
  76   if (index == _hot_cache_size) {
  77     Atomic::store(&_cache_wrapped_around, true);

That comment seems like it has some wording problems. It's also about
the store, so perhaps should be between lines 76 and 77. Maybe reword
something like

Can use relaxed store because all racing threads are writing the same
value and there aren't any concurrent readers.
------------------------------------------------------------------------------

Looks good.  I don't need a new webrev for futzing with the comment.