log slowness

results.md

Windows

• VS2015 x64: 10.19 sec: 3591342062.644168

• mingw-w64 x64 gcc 7.3.0 (msys2): 29.3 sec: 3591342062.644168

• VS2015 32-bit: 13.71 sec: 3591342062.644168

• mingw-w64 32-bit gcc 7.3.0 (msys2): 27.23 sec: 3591342062.644168

• windows go 1.8.3: 16.67 sec: 3591342062.644168

Linux/Virtualbox

• Alpine/musl gcc 6.4.0: 47.62 sec: 3591342062.644168
• Debian/glibc 2.24-11 gcc 6.3.0: 82.15 sec: 3591342062.644168
• debian go 1.7.4: 21.66 sec: 3591342062.644168

ARM

• RPi3/glibc 2.24-11 gcc 6.3.0: 204.3 sec: 3591342062.644168

Linux/Virtualbox - Docker (C)

• alpine docker: 25.06 sec: 3591342062.644168
• debian: 71.39 sec: 3591342062.644168

https://github.com/lattera/glibc/commit/b7c83ca30ef8e85b6642151d95600a36535f8d97

test.c

#include <stdio.h>
#include <math.h>
#include <time.h>
#include <sys/time.h>
#include <unistd.h>

struct timespec diff(struct timespec start, struct timespec end)
{
	struct timespec temp;
	if ((end.tv_nsec-start.tv_nsec)<0) {
		temp.tv_sec = end.tv_sec-start.tv_sec-1;
		temp.tv_nsec = 1000000000+end.tv_nsec-start.tv_nsec;
	} else {
		temp.tv_sec = end.tv_sec-start.tv_sec;
		temp.tv_nsec = end.tv_nsec-start.tv_nsec;
	}
	return temp;
}

int main()
{
	struct timespec start, end;
	clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &start);
        double x = 0;
        for (int j = 0; j < 10000000; j++)
        {
                for (int i = 1; i < 100; i++)
                {
                        x += log(i);
                }
        }
	clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &end);
	struct timespec df = diff(start, end);
	double fdf = df.tv_sec;
	fdf += (df.tv_nsec / 1000000000.0);
        printf("%.4g sec: %f\n", fdf, x);
}

test.cc

#include <cstdio>
#include <cmath>
#include <chrono>

int main()
{
	auto now = std::chrono::high_resolution_clock::now();
	double x = 0;
	for (int j = 0; j < 10000000; j++)
	{
		for (int i = 1; i < 100; i++)
		{
			//double a = std::exp(i);
			x += std::log(i);
			//i += std::exp(i);
		}
	}
	std::chrono::duration<double> dur = std::chrono::high_resolution_clock::now() - now;
	printf("%.4g sec: %f\n", dur.count(), x);
	getchar();
}

test.go

package main

import (
	"fmt"
	"math"
	"time"
)

func main() {
	now := time.Now()

	var x float64
	for i := 0; i < 10000000; i++ {
		for j := 1; j < 100; j++ {
			x += math.Log(float64(j))
		}
	}

	fmt.Printf("%.4g sec: %f\n", time.Since(now).Seconds(), x)
}