Skip to content

Instantly share code, notes, and snippets.

Embed
What would you like to do?
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
int main() {
int fd = shm_open("test-shm", O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
if (fd == -1) {
printf("Unable to open shm\n");
exit(1);
}
size_t size = 8192;
ftruncate(fd, size);
int size_int = size / 4;
int *a = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
int *b = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
printf("a=%lx\n",a);
printf("b=%lx\n",b);
// warmup
for (int i=0;i<size_int;i++) {
a[i] = b[i] = 0;
}
// test
clock_t t1 = clock();
for (int j=0;j<1024*1024;j++) for (int i=0;i<size_int;i++) a[i] = b[i];
clock_t t2 = clock();
for (int j=0;j<1024*1024;j++) for (int i=0;i<size_int;i++) a[i] = a[i];
clock_t t3 = clock();
printf("t2-t1 = %ld\n",t2-t1);
printf("t3-t2 = %ld\n",t3-t2);
shm_unlink("test-shm");
return 0;
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment