github.com/segmentio/parquet-go@v0.0.0-20230712180008-5d42db8f0d47/internal/bytealg/count_amd64.go (about)

     1  //go:build !purego
     2  
     3  package bytealg
     4  
     5  // This function is similar to using the standard bytes.Count function with a
     6  // one-byte separator. However, the implementation makes use of AVX-512 when
     7  // possible, which yields measurable throughput improvements:
     8  //
     9  // name       old time/op    new time/op    delta
    10  // CountByte    82.5ns ± 0%    43.9ns ± 0%  -46.74%  (p=0.000 n=10+10)
    11  //
    12  // name       old speed      new speed      delta
    13  // CountByte  49.6GB/s ± 0%  93.2GB/s ± 0%  +87.74%  (p=0.000 n=10+10)
    14  //
    15  // On systems that do not have AVX-512, the AVX2 version of the code is also
    16  // optimized to make use of multiple register lanes, which gives a bit better
    17  // throughput than the standard library function:
    18  //
    19  // name       old time/op    new time/op    delta
    20  // CountByte    82.5ns ± 0%    61.0ns ± 0%  -26.04%  (p=0.000 n=10+10)
    21  //
    22  // name       old speed      new speed      delta
    23  // CountByte  49.6GB/s ± 0%  67.1GB/s ± 0%  +35.21%  (p=0.000 n=10+10)
    24  //
    25  //go:noescape
    26  func Count(data []byte, value byte) int