RFR: 8205676: ZGC: Remove TLAB allocations in relocation path

[Erik Österlund]

Hi Per,

Looks good.

Thanks,
/Erik

On 2018-06-26 12:45, Per Liden wrote:
> During Java-thread aided relocation, ZGC tries to use the TLAB to 
> allocate the new object. However, this interacts badly with JEP 331: 
> Low-Overhead Heap Profiling, as it distorts the profiling statistics. 
> I propose we remove the use of the TALB in the relocation path, 
> essentially changing a thread-local pointer bump to a uncontended 
> CPU-local CAS.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8205676
> Webrev: http://cr.openjdk.java.net/~pliden/8205676/webrev.0
>
> Testing: Currently running benchmarks to verify that this has no 
> unexpected performance hit.
>
> I've filed two follow up RFEs (also out for review now), to clean up 
> some functions that are now unused:
> https://bugs.openjdk.java.net/browse/JDK-8205678
> https://bugs.openjdk.java.net/browse/JDK-8205679
>
> /Per