Random C++ io benchmark

1 gen.py

import random

numbers = (random.randrange(2**32) for _ in range(3 * 10**6))

with open("in.txt", "w") as f:
    f.write(" ".join(map(str, numbers)))

2 iostream.cpp

#include <iostream>

int main() {
  unsigned parity = 0;
  unsigned x;

  while (std::cin >> x) {
    parity ^= x;
  }
  std::cout << parity << std::endl;
}

3 cstdio.cpp

#include <cstdio>

int main() {
  unsigned parity = 0;
  unsigned x;

  while (1 == std::scanf("%u", &x)) {
    parity ^= x;
  }
  std::printf("%u\n", parity);
}

4 iostream_unsynced.cpp

#include <iostream>

int main() {
  unsigned parity = 0;
  unsigned x;

  std::ios::sync_with_stdio(false);

  while (std::cin >> x) {
    parity ^= x;
  }
  std::cout << parity << std::endl;
}

5 results.txt

λ ~/iobench/ python3 gen.py
λ ~/iobench/ clang++ -Wall -Werror -O2 iostream.cpp -o iostream
λ ~/iobench/ clang++ -Wall -Werror -O2 cstdio.cpp -o cstdio     
λ ~/iobench/ clang++ -Wall -Werror -O2 iostream_unsynced.cpp -o iostream_unsynced
λ ~/iobench/ ./iostream < in.txt && ./cstdio < in.txt && ./iostream_unsynced < in.txt
3930846996
3930846996
3930846996
λ ~/iobench/ time ./iostream < in.txt
3930846996
./iostream < in.txt  1.44s user 0.01s system 99% cpu 1.447 total
λ ~/iobench/ time ./cstdio < in.txt 
3930846996
./cstdio < in.txt  0.48s user 0.01s system 99% cpu 0.492 total
λ ~/iobench/ time ./iostream_unsynced < in.txt 
3930846996
./iostream_unsynced < in.txt  0.34s user 0.00s system 99% cpu 0.351 total

Credit: http://stackoverflow.com/a/12762166