CRR (XXS): 7146246: G1: expose some of the -XX flags that drive which old regions to collect during mixed GCs

[Jesper Wilhelmsson]

Tony,

You also changed the default value of G1OldCSetRegionLiveThresholdPercent from 
95% to 90%. Was this intentional?

I interpret the explanation of G1HeapWastePercent as if it is 5% in total over 
all regions. Is that correct? I thought that was checked on a per region basis.
/Jesper


On 03/21/2012 04:13 PM, Tony Printezis wrote:
> Hi all,
>
> Can I have a couple of quick code review for this very small change?
>
> http://cr.openjdk.java.net/~tonyp/7146246/webrev.0/
>
> It turns the following two cmd line params into product params:
>
> G1HeapWastePercent (previously called: G1OldReclaimableThresholdPercent)
> G1MixedGCCountTarget (previous called: G1MaxMixedGCNum)
>
> These are helpful in allowing the user to fine-tune G1's behavior wrt which
> old regions to collect during mixed GCs, how many mixed GCs to do, etc.
>
> I also increased the default value of the former from 1% to 5%. Charlie ran
> some performance tests and found that the new default eliminated some very
> long mixed GCs that he was experiencing with the old default.
>
> Tony
>