RFR 8042668: GC Support for shared heap ranges in CDS (RE: JDK-8059092)

Tom Benson tom.benson at oracle.com
Mon Jun 8 21:48:46 UTC 2015


Hi,
On this point:

> > > Performance:  The GC changes had no significant impact on SpecJBB,
> >
> > For Specjbb2005, did you check object copy/young gc times specifically?
> > They do not do a lot of GCs in the first place, so an overall 
> performance
> > regression would require a very large performance regression in 
> young gc
> > times to be noticed.
>
> I only specifically checked full GC times for the reasons I mentioned, 
> relying
> on impact to benchmarks to show other impact.  I can look at that as 
> well with
> the new version.
>

I found no significant difference.  I ran jbb'05 at 256 threads and a 
12G heap for 4 runs of 30 mins each, with each version.  This gave me a 
little over 5000 young GC pauses.  The average of those for the new 
version was about 0.5% faster than the existing version.

Tom


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