Try these versions: https://play.golang.org/p/HF6k0ovyoW
Changes: 1. Numbers big enough that the multiplies take some time. 2. Two styles of synchronization and work distribution. Best case in this configuration is 3.9151x speedup on 4 core notebook: $ go test -bench=. testing: warning: no tests to run BenchmarkLoop-8 10 115728469 ns/op BenchmarkParLoop2-8 50 29559001 ns/op BenchmarkParLoop3-8 50 31231335 ns/op Michael Jones michael.jo...@gmail.com > On Jun 28, 2016, at 7:05 PM, Michael Jones <michael.jo...@gmail.com> wrote: > > You should expect linear speedup. But you’ll need to work fot it. Problems in > this version: > > 1. 10,000 parallel workers! Not very cache friendly. > 2. You don’t wait for the goroutines to finish, so not very meaningful. > > Look for the blog posts and videos about concurrently patterns. What you > likely want is a set of worker process (~ncpus or 2x that) doing the work and > a way to know when the work is done. > > Michael Jones > michael.jo...@gmail.com <mailto:michael.jo...@gmail.com> >> On Jun 28, 2016, at 5:01 PM, guyz...@gmail.com <mailto:guyz...@gmail.com> >> wrote: >> >> Hi, >> >> I'm attempting to optimize pair-wise operations over arrays of big integers >> ('vectorize'). Currently, I tried creating two versions of a point-wise >> multiplication function - one that is a simple serial for-loop, and another >> that uses go-routines to create a parallel (or more correctly - concurrent) >> for loop. The code is below along with the results, showing that the >> parallel for loop is actually ~10x slower. >> >> My question is - is there a better way to achieve this, or is a naive serial >> for-loop the best one can hope for? >> >> func BenchmarkLoop(b *testing.B) { >> var x, y, z [10000]big.Int >> for i := 0; i < 10000; i++ { >> x[i].SetInt64(892745680) >> y[i].SetInt64(353322197) >> } >> >> for n := 0; n < b.N; n++ { >> for i := 0; i < 10000; i++ { >> z[i].Mul(&x[i], &y[i]) >> } >> } >> } >> >> func BenchmarkParLoop1(b *testing.B) { >> var x, y, z [10000]big.Int >> runtime.GOMAXPROCS(4) // Tried playing with this value from 1-8 >> for i := 0; i < 10000; i++ { >> x[i].SetInt64(892745680) >> y[i].SetInt64(353322197) >> } >> >> for n := 0; n < b.N; n++ { >> for i := 0; i < 10000; i++ { >> go func(i int) { >> z[i].Mul(&x[i], &y[i]) >> }(i) >> } >> } >> } >> >> Benchmarks: >> BenchmarkLoop-8 5000 350033 ns/op >> >> BenchmarkParLoop1-8 500 2352201 ns/op >> >> >> >> >> >> Thanks! >> >> >> -- >> 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 >> <mailto:golang-nuts+unsubscr...@googlegroups.com>. >> For more options, visit https://groups.google.com/d/optout >> <https://groups.google.com/d/optout>. > -- 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. For more options, visit https://groups.google.com/d/optout.
