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new 38ebd72 Update user guide performance notes
38ebd72 is described below
commit 38ebd7239535db5e0127e92d94ec44cfe23b5458
Author: aherbert <aherb...@apache.org>
AuthorDate: Thu Jul 29 10:52:16 2021 +0100
Update user guide performance notes
---
src/site/apt/userguide/rng.apt | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/src/site/apt/userguide/rng.apt b/src/site/apt/userguide/rng.apt
index e3e85cd..ae39c95 100644
--- a/src/site/apt/userguide/rng.apt
+++ b/src/site/apt/userguide/rng.apt
@@ -603,6 +603,8 @@ double[] coordinate = sampler.sample();
Performance was measured using the
{{{http://openjdk.java.net/projects/code-tools/jmh/}Java Micro-benchmark
Harness (JMH)}}.
+ Timings are representative of performance; the relative ranking of results
may change depending on the JVM, operating system and hardware.
+
In these tables:
* The first column is the RNG identifier (see
{{{../commons-rng-simple/apidocs/org/apache/commons/rng/simple/RandomSource.html}RandomSource}})
@@ -730,9 +732,9 @@ double[] coordinate = sampler.sample();
Notes:
- The <<<RandomSource.JDK>>> generator uses thread-safe (synchronized)
<<<int>>> generation which has a performance overhead (see the <<<int>>>
generation results). For the <<<boolean>>> generation the synchronization
occurs 1 in 32 calls and the resulting performance is good. However the output
will be low quality and this generator should not be used. See the
{{{a5._Quality}Quality}} section for details.
+ The <<<RandomSource.JDK>>> generator uses thread-safe (synchronized)
<<<int>>> generation which has a performance overhead (see the <<<int>>>
generation results). Note that the output will be low quality and this
generator should not be used. See the {{{a5._Quality}Quality}} section for
details. Multi-threaded applications should use a generator for each thread.
- The speed of <<<boolean>>> generation is related to the speed that the
generator can be loaded to memory and used to generate a new value. This
favours those with a small state such as the linear congruential based
generators (<<<JDK>>>, <<<PCG>>>) and those that batch compute values into an
array (<<<ISAAC>>>). A RNG to compute boolean samples should be chosen based on
the {{{a5._Quality}quality}} of the output.
+ The speed of <<<boolean>>> generation is related to the base implementation
that caches the 32-bit or 64-bit output from the generator. In these results
the 32-bit generators have the better performance. These timings are relative
and all implements are very fast. A RNG to compute boolean samples should be
chosen based on the {{{a5._Quality}quality}} of the output.
* 4.2 Generating Gaussian samples
