RFR (XXS): 8136680: Enable adaptive IHOP by default

[Thomas Schatzl]

Hi Jon,

  thanks for the review.

On Tue, 2015-11-24 at 10:33 -0800, Jon Masamitsu wrote:
> Thomas, Looks good.
> 
> 
> 36 product(bool, G1UseAdaptiveIHOP, true, \
>    37           "Adaptively adjust InitiatingHeapOccupancyPercent from the "      \
> 38 "initial value. The policy tries to start marking as late as " \
> 39 "possible.")
> 
> Let me suggest an alternate comment though.
> 
> "Dynamically adjust the initiating heap occupancy from the  initial 
> value of
> InitiatingHeapOccupancyPercent.  The policy attempts to start marking in
> time based on application behavior."
> 

Much better. Updated webrev at
http://cr.openjdk.java.net/~tschatzl/8136680/webrev.1/

> Do we need G1 in the name of the flag?  Would UseAdaptiveIHOP be
> sufficient?   Or maybe UseDynamicIHOP?  Or  (I write this with some
> trepidation) would the flag be better named 
> UseAdaptiveInitiatingHeapOccupancy
> or UseDynamicInitiatingHeapOccupancy?
> 

As for Adaptive vs. Dynamic, I think Adaptive captures the spirit of the
change better. Also I have not seen other similar flags using Dynamic,
but Adaptive.

As for adding "G1" in front of the flag or not, not sure. CMS also has
its flags prepended with "CMS". Maybe other people have stronger
opinions about this, I would be okay with either.

I also thought about using the long forms, but I think they are too
long :)

> I'm asking the question now because I don't want to ask it the next time
> we do a cleanup of flag names.  I can live with any of the above.

Thanks,
  Thomas