RFR: 8239825: G1: Simplify threshold test for mutator refinement

[Kim Barrett]

> On Mar 5, 2020, at 10:13 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
> 
> Hi,
> 
> On 04.03.20 03:16, Kim Barrett wrote:
>> Please review this change to the handling of "padding" for the threshold
>> used to decide whether a mutator thread should perform concurrent
>> refinement.  Rather than doing a slightly tricky (because of potential
>> overflow) computation every time a mutator thread completes a buffer,
>> instead perform that computation once and record the result for repeated
>> use.
>> CR:
>> https://bugs.openjdk.java.net/browse/JDK-8239825
>> Webrev:
>> https://cr.openjdk.java.net/~kbarrett/8239825/open.00/
>> Testing:
>> mach5 tier1-5 along with changes for JDK-8240133 and JDK-8139652.
>> Local (linux-x64) hotspot:tier1 with just this change.
> 
>  I think this is good.
> 
> Thomas

Thanks.