RFR: Use heuristics to determine the number of conc threads for each conc gc cycle

[Roman Kennke]

Am Donnerstag, den 15.12.2016, 12:43 -0500 schrieb Zhengyu Gu:
> This is an experimental heuristics that determines the number of
> concurrent threads for each concurrent GC cycle.
> 
> SPECjbb runs do not show obvious improvement, it seems to ramp up
> load quickly, so conc thread count stays high.
> 
> 
> The change set also contains some cleanup.
> 
> 
> http://cr.openjdk.java.net/~zgu/shenandoah/conc-worker-heuristics/web
> rev.00/
> 
> 
> Test:
>    SPECjbb, some of SPECjvm benchmarks.
> 
> 
> Thanks,
> 
> -Zhengyu
> 

Interesting. I think the patch is ok.

However, under which situation do you expect an improvement? Can we
construct a benchmark for this?

I think that applications with high alloc pressure (like SPECjbb) will
push us to maximum threads. Low alloc pressure would let us stay lower
too, but those apps would likely not be dominated by GC work anyway.

Roman