JDK 9 RFR of 6375303: Review use of caching in BigDecimal

Aleksey Shipilev aleksey.shipilev at oracle.com
Thu Mar 20 07:49:58 UTC 2014

On 03/20/2014 11:06 AM, Peter Levart wrote:
> I was thinking about last night, for question: "Why is this
> double-checked non-volatile-then-volatile trick not any faster than pure
> volatile variant even on ARM platform where volatile read should have
> some penalty compared to normal read?", might be in the fact that
> Raspberry Pi is a single-core/single-thread "machine". Would anyone with
> JVM JIT compiler expertise care to share some insight? I suspect that on
> such platform, the compiler optimizes volatile accesses so that they are
> performed without otherwise necessary memory fences...

Yes, at least C2 is known to not emit memory fences on uniprocessor
machines. You need to have a multicore ARM. If you are still interested,
contact me privately and I can arrange the access to my personal
quad-core Cortex-A9.


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