RFR 8146991: Introduce per-worker preserved mark stacks in ParallelGC

[Thomas Schatzl]

Hi,

On Fri, 2016-03-04 at 16:42 -0500, Tony Printezis wrote:
> Hi Thomas,
> 
> Cool, thanks. So, what else should we do on this front? Do you want
> me to also refactor G1 to use the new abstractions? Or are you guys


That would be nice. G1 already uses the ReservedMarks stack, and
implements the ReservedMarksSet by hand. It should be an easy change.

Note that G1 already parallelizes mark restoration, so you would need
to implement a G1 specific restoration method (just calling the
existing two methods or so that do the work).

> happy with the way G1 is right now (last time I looked at the code I
> thought there was some opportunity for re-use). Also, there’s an
> additional change to cut down on the number of preserved marks that
> are pushed on he stacks (given that, as we discussed on a separate e
> -mail thread, when biased locking is enabled most objects do not have
> 0x1 as their mark word). Interested in both?

Yes, sure.

Thanks,
  Thomas