RFR (XS): 8140689: Skip last young-only gc if nothing to do in the mixed gc phase

[Thomas Schatzl]

Hi Mikael,

On Thu, 2015-11-05 at 13:19 +0100, Mikael Gerdin wrote:
> Hi Thomas,
> 
> On 2015-10-29 17:47, Thomas Schatzl wrote:
> > Hi all,
> >
> >    can I have reviews for another change that minimizes the turnaround
> > time between one marking round and another one?
> >
> > In this case, if GC cleanup detects that there is nothing to reclaim, it
> > will immediately request an initial mark for the next young-only gc.
> > Previously there had been the requirement that the next young-only gc
> > after marking must be a "regular" young-only gc.
> > This wastes some time until we have a new up-to-date view of the
> > liveness, potentially ending in full gcs.
> >
> > CR:
> > https://bugs.openjdk.java.net/browse/JDK-8140689
> > Webrev:
> > http://cr.openjdk.java.net/~tschatzl/8140689/webrev
> 

  thanks for the review.

Thomas