JDK 9 RFR of 6375303: Review use of caching in BigDecimal (original) (raw)

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.

-Aleksey.

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