With go version go1.16.3 darwin/amd64 (macOS 10.14.6), and after changing N/5 to N/2, I can't reproduce either.
$ go test . -bench=. -benchtime=3s ==================== N = 1615119 goos: darwin goarch: amd64 pkg: bm cpu: Intel(R) Core(TM) i7-5557U CPU @ 3.10GHz Benchmark_InsertOneline-4 867 4130473 ns/op Benchmark_InsertOneline_Disassemble-4 848 4161459 ns/op Benchmark_InsertVerbose-4 696 4988955 ns/op Benchmark_InsertVerbose_b-4 712 4882270 ns/op Benchmark_InsertVerbose_c-4 702 4876656 ns/op PASS ok bm 23.058s InsertOneline_Disassemble-4 is about 0.75% slower than InsertOneline-4, and both are significantly faster than the others. On Friday, 14 May 2021 at 23:49:16 UTC+1 peterGo wrote: > My results: > > https://play.golang.org/p/o2cGAcpNMkX > > I can't reproduce your results. > > 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/4b95fc72-beae-4f12-83cb-c2e9b9e74c66n%40googlegroups.com.
