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

[Kim Barrett]

> On Nov 20, 2019, at 10:26 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
> 
> http://cr.openjdk.java.net/~tschatzl/8227739/webrev.0_to_1/ (diff)
> http://cr.openjdk.java.net/~tschatzl/8227739/webrev.1/ (full)

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src/hotspot/share/gc/g1/g1Policy.cpp
 760    _analytics->report_card_merge_to_scan_ratio(merge_to_scan_ratio, this_pause_was_young_only);

misindentation.

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src/hotspot/share/gc/g1/g1HotCardCache.hpp
  87   bool _cache_wrapped_around;

Although always updated to the same value, it's still written by
multiple threads, so should be "atomic" in the sense we're presently
using, e.g. declare the variable volatile, and consider using
Atomic::store for the write.

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