[aarch64-port-dev ] barrier use in JDK11

[Dave Nuechterlein]

I work for Ampere Computing, and am looking at the C2 code produced for some simple JMH benchmarks.  The code produced from jdk11 seems to have many more DMBs than the jdk8u Aarch64 port.  I think this is probably related to the controls for using barriers instead of LoadAcquire/StoreRelease for volatile variables.  I want to switch the "use barriers for volatile variable switch", but I wanted to know more about why it is there, and what the pitfalls might be.

Any suggestions/comments?

Thanks,
Dave