You are using g 64 bit in Go and 32 bit in C
> On Feb 3, 2019, at 12:33 PM, Miki Tebeka <miki.teb...@gmail.com> wrote:
>
> A bit of profiling shows that the modulo operator takes most of the time:
>
> 1.77s 1.77s (flat, cum) 100% of Total
> . . 2:
> . . 3:import (
> . . 4: "testing"
> . . 5:)
> . . 6:
> 10ms 10ms 7:func loop(m, n int) int {
> . . 8: sum := int(0)
> 30ms 30ms 9: for i := 0; i < 10000000; i++ {
> 1.73s 1.73s 10: if i%n != m {
> . . 11: sum += n
> . . 12: }
> . . 13: }
> . . 14: return sum
> . . 15:}
>
>
>
>
>> On Sunday, February 3, 2019 at 8:22:54 PM UTC+2, Miki Tebeka wrote:
>> Hi,
>>
>> I'm comparing two loops in Go and C. The Go code on my machine is about 3
>> times slower than C. I know C can be faster but didn't think it'll be that
>> faster. Any ideas what's making the Go code slower?
>>
>> You can see the code at https://github.com/tebeka/go-c-loop
>>
>> Go Code:
>> package main
>>
>>
>> import (
>> "fmt"
>> "os"
>> "strconv"
>> "time"
>> )
>>
>>
>> func main() {
>> n, _ := strconv.Atoi(os.Args[1])
>> m, _ := strconv.Atoi(os.Args[2])
>>
>>
>> sum := int(0)
>> start := time.Now()
>> for i := 0; i < 10000000; i++ {
>> if i%n != m {
>> sum += n
>> }
>> }
>>
>>
>> fmt.Println(time.Now().Sub(start).Seconds(), sum)
>> }
>>
>>
>>
>> C Code
>> #include <stdio.h>
>> #include <unistd.h>
>> #include <x86intrin.h>
>>
>>
>>
>>
>> int main(int argc,char** argv) {
>> unsigned long long ull0,ull1;
>> unsigned int sum=0,n,m;
>>
>>
>> sscanf(argv[1],"%d",&n);
>> sscanf(argv[2],"%d",&m);
>>
>>
>> ull0 = __rdtsc();
>> for(int i=0; i<10000000; i++) {
>> if(i%n != m) {
>> sum += n;
>> }
>>
>>
>> }
>>
>>
>> ull1 = __rdtsc();
>> printf("%f %d\n",(ull1-ull0)/2.1e9,sum);
>> }
>>
>>
>>
>
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