RFR (S): 8155230: Tune thread usage for mark bitmap clear

[Thomas Schatzl]

Hi Mikael,

On Thu, 2016-04-28 at 16:19 +0200, Mikael Gerdin wrote:
> Hi Thomas,
> 
> On 2016-04-28 13:15, Thomas Schatzl wrote:
> > 
> > Hi all,
> > 
> >    during testing of 8077144 I found that mark bitmap clearing can
> > be
> > significantly sped up by not using that many threads.
> > 
> > A good conservative estimate (tends to use too many threads) that
> > still
> > cuts mark bitmap clear time by >50% is to give each thread at least
> > 1
> > MB of data to clear.
> > 
> > CR:
> > https://bugs.openjdk.java.net/browse/JDK-8155230
> > Webrev:
> > http://cr.openjdk.java.net/~tschatzl/8155230/webrev/
> Looks good.
> 

  thanks for your review.

Thomas