buffered randomness throughput benchmarks

randpool_test.go

package main

import (
	"bufio"
	"crypto/rand"
	"strconv"
	"testing"
)

func BenchmarkRandReads(b *testing.B) {
	const size = 16 // assume we need 16 bytes of entropy per seed operation
	var dst [size]byte

	b.Run("normal", func(b *testing.B) {
		b.SetBytes(size)
		for i := 0; i < b.N; i++ {
			_, _ = rand.Read(dst[:])
		}
	})

	b.Run("buffered", func(b *testing.B) {
		bufSizes := []int{128, 256, 512, 1024, 2048, 4096}
		for _, bs := range bufSizes {
			b.Run(strconv.Itoa(bs), func(b *testing.B) {
				b.SetBytes(size)
				bufReader := bufio.NewReaderSize(rand.Reader, bs)
				for i := 0; i < b.N; i++ {
					_, _ = bufReader.Read(dst[:])
				}
			})
		}
	})
}

Results on laptop:

$ go test -bench=. -cpu=1
goos: darwin
goarch: arm64

BenchmarkRandReads/normal                2845966               403.4 ns/op        39.67 MB/s
BenchmarkRandReads/buffered/128         22289520                54.02 ns/op      296.17 MB/s
BenchmarkRandReads/buffered/256         38142613                31.10 ns/op      514.41 MB/s
BenchmarkRandReads/buffered/512         38099823                30.96 ns/op      516.72 MB/s
BenchmarkRandReads/buffered/1024        39591655                30.47 ns/op      525.09 MB/s
BenchmarkRandReads/buffered/2048        38853812                30.29 ns/op      528.30 MB/s
BenchmarkRandReads/buffered/4096        39630936                30.11 ns/op      531.43 MB/s