RFR (S/M): 8142484: Let IHOP follow the current heap size, not the maximum heap size

[Bengt Rutisson]

Hi Thomas,

On 2016-03-03 15:07, Thomas Schatzl wrote:
> Hi all,
>
>    can I have reviews for this change that updates what maximum
> threshold (capacity) the IHOP mechanisms follow?
>
> Instead of following the maximum capacity, IHOP follows the current
> capacity now.
>
> Changes are relatively small, instead of passing a fixed threshold
> capacity at initialization, add and use a method in the G1IHOPControl
> class to update to the current threshold.
>
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8142484
> Webrev:
> cr.openjdk.java.net/~tschatzl/8142484/webrev

I think this looks good.

One very minor nit for line 569 in g1CollectorPolicy.cpp:

  569 _ihop_control->update_target_occupancy(HeapRegion::GrainBytes * 
new_number_of_regions);

This would read more naturally for me if the multiplication was swapped 
around, so:

  569 _ihop_control->update_target_occupancy(new_number_of_regions * 
HeapRegion::GrainBytes);

I don't need an updated review for that.

Thanks,
Bengt

> Testing:
> jprt, local testing that it works, vm.gc run
>
> Thanks,
>    Thomas