RFR: 8227369: pd_disjoint_words_atomic() needs to be atomic [v2]

[David Holmes]

On Mon, 28 Feb 2022 12:49:25 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> I ran some GC benchmarks which turned out to be just specjbb2005 and specjvm2008-*.
>> 
>> There were two regressions flagged:
>> 
>> Linux-x64: SPECjvm2008-LU.large-ZGC  -5.82%
>> macos-x64: SPECjvm2008-Serial-ParGC  -4.16%
>> 
>> However, Erik thinks these are just noise as apparently ZGC doesn't use these atomic copy routines, nor does he think ParGC does either.
>> 
>> Thoughts?
>
>> I ran some GC benchmarks which turned out to be just specjbb2005 and specjvm2008-*.
>> 
>> There were two regressions flagged:
>> 
>> Linux-x64: SPECjvm2008-LU.large-ZGC -5.82%
>> macos-x64: SPECjvm2008-Serial-ParGC -4.16%
> 
> Myself, I never trust LU.large results, since they experience quite large run-to-run variance in our runs. Serial regression is weird, though, it is usually a very stable workload. Does it reproduce locally? If it does not reproduce, we can go ahead and deal with any regressions later.

@shipilev  I can't run these benchmarks "locally" (I don't have the benchmarks nor a macOS system). I will try submitting another run just for that benchmark.

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PR: https://git.openjdk.java.net/jdk/pull/7567