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

Stefan Karlsson stefan.karlsson at oracle.com
Wed Jun 27 13:18:35 UTC 2018


Looks good.

StefanK

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



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