> you don't provide the Go version, My Go version is Go 1.16.3. (BTW, "go test" really should print Go version in the first line).
> you don't provide memory allocation statistics, There are no surprises in memory allocation statistics so I didn't mention them. > you only provide results for a single data point. There are no surprises for small Ns. So I I didn't provide the results for them. > I am unable reproduce your result. At least, you exactly reproduced my first observation: if N is large enough, the one line implementations are fast as the others. And you partially reproduced my second observation: the InsertOneline implementations run faster for odd Ns than even Ns for large Ns. On Saturday, May 15, 2021 at 11:49:38 AM UTC-4 peterGo wrote: > 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/55b3ee8c-6f96-4dc1-b547-0ddaab3bf4dbn%40googlegroups.com.
