sometimes faster rand(::Xoshiro, ::UnitRange{Int128})
#41067
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
rfourquet
added
performance
rfourquet
changed the title
rand(::Xoshiro, ::UnitRange{Int128})rand(::Xoshiro, ::UnitRange{Int128})
For Int128/UInt128 ranges, the default sampler provided by `Random` is `SamplerRangeFast`; till now, this was optimized for a version of MersenneTwister which produced natively 52 bits of entropy, so if the range length was between 2^52 and 2^104, two 52-bits words were generated (and used with rejection sampling). But when the RNG can produce a 64-bits word in a fast way, only one such word needs to be generated for a length between 2^52 and 2^64: in this range, the new `rand` method for `SamplerRangeFast` is about 35% faster. Also, `MersenneTwister` can now generate `UInt64` fast, but the two methods are equally fast, so it was not changed for that RNG.
rfourquet
force-pushed
the
rf/rand/fast64
branch
from
9418ac8
to
ef52c34
Compare
|
Is this good to merge? Also, do we want to backport to 1.7? |
On my side yes, the win32 CI failure seems unrelated. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
For Int128/UInt128 ranges, the default sampler provided by
Randomis
SamplerRangeFast; till now, this was optimized for a versionof MersenneTwister which produced natively 52 bits of entropy,
so if the range length was between 2^52 and 2^104, two 52-bits
words were generated (and used with rejection sampling).
But when the RNG can produce a 64-bits word in a fast way,
only one such word needs to be generated for a length
between 2^52 and 2^64: in this range, the new
randmethodfor
SamplerRangeFastis about 35% faster.Also,
MersenneTwistercan now generateUInt64fast, but the twomethods are equally fast, so it was not changed for that RNG.