/* Measure Linux (or whatever) system call overhead: minimally about
 * 300 ns on this laptop.  Copying 8192 zero bytes into userspace
 * seems to take about 1400 ns more, or 171 ps per byte.
 */
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

char *devzero = "/dev/zero";

int main(int argc, char **argv) {
  int n = atoi(argv[1]);
  size_t s = atoi(argv[2]);
  char c[s];
  int fd = open(devzero, O_RDONLY);
  if (fd < 0) {
    perror(devzero);
    return 1;
  }

  for (int i = 0; i < n; i++) {
    read(fd, c, s);
  }
  return 0;
}