RFR (S): 8033380: Experimental VM flag to enforce access atomicity
Christian Thalinger
christian.thalinger at oracle.com
Wed Feb 12 15:05:54 PST 2014
On Feb 11, 2014, at 3:02 AM, Aleksey Shipilev <aleksey.shipilev at oracle.com> wrote:
> Hi,
>
> I understand we are still closed for integration?
>
> Please review this small feature meanwhile:
> https://bugs.openjdk.java.net/browse/JDK-8033380
> http://cr.openjdk.java.net/~shade/8033380/webrev.02/
>
> TL;DR: JMM 9 may need to extend the access atomicity over longs and
> doubles. Luckily, our logic in emitting the relevant access-atomic
> instructions is decoupled from memory barriers logic, and so we can
> "just" unconditionally go through needs_atomic_access where appropriate.
I’m not sure we should push this upstream. You say JMM 9 “may need” this feature. This feels premature to have it as an experimental feature in the JVM then. Experimental to me means it’s a feature that might be useful to customers and they can try it if they want. That doesn’t apply to this proposed “feature”; it’s only useful for your testing purposes.
>
> Testing:
> - full cycle JPRT
> - targeted microbenchmarks on x86/ARM/PPC
>
> Thanks,
> -Aleksey
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