github.com/songzhibin97/go-baseutils@v0.0.2-0.20240302024150-487d8ce9c082/sys/fastrand/README.md (about)

     1  # fastrand
     2  
     3  Fastest pseudo-random number generator in Go. 
     4  
     5  This generator actually come from Go runtime per-M structure, and the init-seed is provided by Go runtime, which means you can't add your own seed, but these methods scales very well on multiple cores.
     6  
     7  The generator passes the SmallCrush suite, part of TestU01 framework: http://simul.iro.umontreal.ca/testu01/tu01.html
     8  
     9  pseudo-random paper: https://www.jstatsoft.org/article/view/v008i14/xorshift.pdf
    10  
    11  fast-modulo-reduction: https://lemire.me/blog/2016/06/27/a-fast-alternative-to-the-modulo-reduction/
    12  
    13  
    14  
    15  ## Compare to math/rand
    16  
    17  - Much faster (~5x faster for single-core; ~200x faster for multiple-cores)
    18  - Scales well on multiple cores
    19  - **Not** provide a stable value stream (can't inject init-seed)
    20  - Fix bugs in math/rand `Float64` and `Float32`  (since no need to preserve the value stream)
    21  
    22  
    23  
    24  ## Bencmark
    25  
    26  Go version: go1.15.6 linux/amd64
    27  
    28  CPU: AMD 3700x(8C16T), running at 3.6GHz
    29  
    30  OS: ubuntu 18.04
    31  
    32  MEMORY: 16G x 2 (3200MHz)
    33  
    34  
    35  
    36  ##### multiple-cores
    37  
    38  ```
    39  name                                 time/op
    40  MultipleCore/math/rand-Int31n(5)-16   152ns ± 0%
    41  MultipleCore/fast-rand-Int31n(5)-16  0.40ns ± 0%
    42  MultipleCore/math/rand-Int63n(5)-16   167ns ± 0%
    43  MultipleCore/fast-rand-Int63n(5)-16  3.04ns ± 0%
    44  MultipleCore/math/rand-Float32()-16   143ns ± 0%
    45  MultipleCore/fast-rand-Float32()-16  0.40ns ± 0%
    46  MultipleCore/math/rand-Uint32()-16    133ns ± 0%
    47  MultipleCore/fast-rand-Uint32()-16   0.23ns ± 0%
    48  MultipleCore/math/rand-Uint64()-16    140ns ± 0%
    49  MultipleCore/fast-rand-Uint64()-16   0.56ns ± 0%
    50  ```
    51  
    52  
    53  
    54  ##### single-core
    55  
    56  ```
    57  name                               time/op
    58  SingleCore/math/rand-Int31n(5)-16  15.5ns ± 0%
    59  SingleCore/fast-rand-Int31n(5)-16  3.91ns ± 0%
    60  SingleCore/math/rand-Int63n(5)-16  24.4ns ± 0%
    61  SingleCore/fast-rand-Int63n(5)-16  24.4ns ± 0%
    62  SingleCore/math/rand-Uint32()-16   10.9ns ± 0%
    63  SingleCore/fast-rand-Uint32()-16   2.86ns ± 0%
    64  SingleCore/math/rand-Uint64()-16   11.3ns ± 0%
    65  SingleCore/fast-rand-Uint64()-16   5.88ns ± 0%
    66  ```
    67  
    68  
    69  
    70  ##### compare to other repo
    71  
    72  (multiple-cores)
    73  
    74  rand-1 -> this repo
    75  
    76  rand-2 -> https://github.com/valyala/fastrand
    77  
    78  ```
    79  name                         time/op
    80  VS/fastrand-1-Uint32()-16    0.23ns ± 0%
    81  VS/fastrand-2-Uint32()-16    3.04ns ±23%
    82  VS/fastrand-1-Uint32n(5)-16  0.23ns ± 1%
    83  VS/fastrand-2-Uint32n(5)-16  3.13ns ±32%
    84  ```
    85