Your benchmark exactly reproduced both of my observations. On Saturday, May 15, 2021 at 9:15:21 AM UTC-4 Brian Candler wrote:
> 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/e827a0e9-808f-400d-a951-4f53addfa7e6n%40googlegroups.com.
