RFR (S): 8155810: Bound the number of root region scan threads to the number of survivor regions

[Thomas Schatzl]

Hi Stefan,

On Tue, 2016-05-03 at 09:50 +0200, Stefan Johansson wrote:
> 
> On 2016-05-02 14:35, Thomas Schatzl wrote:
> > 
> > Hi all,
> > 
> >    can I have reviews for this change that originated from the
> > discussion about JDK-8150393 where it has been found
> > that G1ConcurrentMark::scan_root_regions() always starts all
> > threads
> > for scanning the root regions independent of the number of root
> > regions
> > available. This potentially leads to starting (and needing to
> > synchronize for) to too many threads on huge machines (and on
> > smaller
> > ones if the conditions are met of course).
> > 
> > CR:
> > https://bugs.openjdk.java.net/browse/JDK-8155810
> > Webrev:
> > http://cr.openjdk.java.net/~tschatzl/8155810/webrev/
> Looks good,

  thanks for your review.

Thomas