RFR (S): 8155233: Lazy coarse map clear

[Mikael Gerdin]

Hi Thomas,

On 2016-04-28 13:15, Thomas Schatzl wrote:
> Hi all,
>
>    can I have reviews for this tiny fix?
>
> A significant part of remembered set clearing is spent on clearing the
> coarse remembered set, particularly on large heaps.
>
> One way to avoid this work most of the time is to only clear the coarse
> bitmaps if they have actually been dirtied.
>
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8155233
> Webrev:
> http://cr.openjdk.java.net/~tschatzl/8155233/webrev/

Looks good.
/Mikael

> Testing:
> jprt, vm.gc, perf tests
>
> Thanks,
>    Thomas
>