For your sliceinsert microbenchmarks, you don't provide the Go version, you don't provide memory allocation statistics, and you only provide results for a single data point.
My results for several values of N: https://play.golang.org/p/WuKmIy_jY20 There are significant differences in CPU performance for different values of N, ranging from 1:1 to 2:1 for append versus precise implementations. I am unable reproduce your result. Peter On Thursday, May 13, 2021 at 4:52:32 AM UTC-4 tapi...@gmail.com wrote: > > package main > > import "testing" > > const N = 1615119 > // It is strange that if N is large enough, > // the one line implementations are fast as the others. > // And if N is odd number, the InsertOneline_Disassemble > // implementation is about 10% faster than the others. > > func init() { > println("==================== N =", N) > } > > func InsertOneline(s []int, k int, vs ...int) []int { > return append(s[:k], append(vs, s[k:]...)...) > } > > func InsertOneline_Disassemble(s []int, k int, vs ...int) []int { > z := append(vs, s[k:]...) > return append(s[:k], z...) > } > > func InsertVerbose(s []int, k int, vs ...int) []int { > if n := len(s) + len(vs); n <= cap(s) { > s2 := s[:n] > copy(s2[k+len(vs):], s[k:]) > copy(s2[k:], vs) > return s2 > } > s2 := make([]int, len(s) + len(vs)) > copy(s2, s[:k]) > copy(s2[k:], vs) > copy(s2[k+len(vs):], s[k:]) > return s2 > } > > > func InsertVerbose_b(s []int, k int, vs ...int) []int { > if n := len(s) + len(vs); n <= cap(s) { > s2 := s[:n] > copy(s2[k+len(vs):], s[k:]) > copy(s2[k:], vs) > return s2 > } > s2 := make([]int, 0, len(s) + len(vs)) > s2 = append(s2, s[:k]...) > s2 = append(s2, vs...) > s2 = append(s2, s[k:]...) > return s2 > } > > func InsertVerbose_c(s []int, k int, vs ...int) []int { > if n := len(s) + len(vs); n <= cap(s) { > s2 := s[:n] > copy(s2[k+len(vs):], s[k:]) > copy(s2[k:], vs) > return s2 > } > s2 := append([]int(nil), make([]int, len(s) + len(vs))...)[:0] > s2 = append(s2, s[:k]...) > s2 = append(s2, vs...) > s2 = append(s2, s[k:]...) > return s2 > } > > var s1 []int > func Benchmark_InsertOneline(b *testing.B) { > var x = make([]int, N) > var y = make([]int, N/2) > var k = N/5 > b.ResetTimer() > for i := 0; i < b.N; i++ { > s1 = InsertOneline(x, k, y...) > } > } > > var s1b []int > func Benchmark_InsertOneline_Disassemble(b *testing.B) { > var x = make([]int, N) > var y = make([]int, N/2) > var k = N/2 > b.ResetTimer() > for i := 0; i < b.N; i++ { > s1b = InsertOneline_Disassemble(x, k, y...) > } > } > > var s2 []int > func Benchmark_InsertVerbose(b *testing.B) { > var x = make([]int, N) > var y = make([]int, N/2) > var k = N/2 > b.ResetTimer() > for i := 0; i < b.N; i++ { > s2 = InsertVerbose(x, k, y...) > } > } > > var s3 []int > func Benchmark_InsertVerbose_b(b *testing.B) { > var x = make([]int, N) > var y = make([]int, N/2) > var k = N/2 > b.ResetTimer() > for i := 0; i < b.N; i++ { > s3 = InsertVerbose_b(x, k, y...) > } > } > > var s4 []int > func Benchmark_InsertVerbose_c(b *testing.B) { > var x = make([]int, N) > var y = make([]int, N/2) > var k = N/2 > b.ResetTimer() > for i := 0; i < b.N; i++ { > s4 = InsertVerbose_c(x, k, y...) > } > } > > > The result: > > $ go test -bench=. -benchtime=3s > ==================== N = 1615119 > goos: linux > goarch: amd64 > pkg: a.y/bench/sliceinsert > cpu: Intel(R) Core(TM) i5-4210U CPU @ 1.70GHz > Benchmark_InsertOneline-4 693 4741509 ns/op > Benchmark_InsertOneline_Disassemble-4 871 4194142 ns/op > Benchmark_InsertVerbose-4 764 4627334 ns/op > Benchmark_InsertVerbose_b-4 769 4958537 ns/op > Benchmark_InsertVerbose_c-4 661 4855514 ns/op > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/89741678-c394-4ec7-8d7d-adb083e9e4e1n%40googlegroups.com.
