On Sun, 4 Sep 2016 00:33:32 +0300, Artem Barger wrote:
On Sat, Sep 3, 2016 at 1:36 AM, Gilles <gil...@harfang.homelinux.org>
wrote:
The discrepancy between "PerfTestUtils" and JMH could be a bug (in
"PerfTestUtils" of course!) or ... measuring different use-cases:
Use of several RNGs at the same time vs using a single one; the
latter could allow for more aggressive optimizations.
I'm not really familiar with the PerfTestUtils, while I know that
JMH is
doing a great
job to avoid different pitfalls while building microbenchmarks for
measuring a performance.
Also it looks a bit suspicious where comparing JDK random generator
against
itself it's not
showing ration of 1.0 for PerfTestUtils.
That is easy to explain: the ratio was done wrt to a
"java.util.Random" object, while "RandomSource.JDK" wraps
an instance of "java.util.Random".
Lacking input as to what the benchmarks purport to demonstrate, I'm
about to simply delete the "PerfTestUtils" column.
The result will be a simplified (maybe simplistic) view of the
relative performance of the RNGs in the "single use" use-case.
I can try to take a look on PerfTestUtils to understand what is the
main
cause of such difference.
AFAICS, the main difference is that JMH benchmarks one code
(marked with "@Benchmark") after the other while "PerfTestUtils"
benchmarks all the codes together.
Any comment, objection, explanation, suggestion?
[E.g. set up JMH to benchmark the other use case, or a reason why
this is in fact not necessary.]
We can play with different amount of warm up rounds in JMH to see
whenever
there is a degradation
to results similar to PerfTestUtils for example.
I'm pretty sure it's not related to warmup because the
"PerfTestUtils" benchmarks were running for much longer
than JMH.
What would be interesting is to see whether JMH performance
degrades when multiple RNGs (of different types) have been
instantiated and run in the same scope.
Regards,
Gilles
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