/**
* The main function.
*/
int main()
{
/* Seeding random number generator */
srand( time(NULL) );
int my_pid = getpid();
unsigned int period = get_period();
unsigned int computation_time = get_comp_time(period);
register_process(my_pid, period, computation_time);
if(!is_registered(my_pid))
{
printf("%d: I was unable to register. ;_;\n", my_pid);
exit(1);
}
printf("%d: Registered! \n", my_pid);
unsigned int iterations = get_iterations();
yield(my_pid);
while(iterations > 0)
{
struct timeval time;
gettimeofday(&time);
unsigned int start_time = time.tv_usec;
unsigned int time_elapsed = 0;
while(time_elapsed < computation_time)
{
int i;
for(i = 0; i < 100; i++)
{
factorial((i % 20)+1);
}
gettimeofday(&time);
time_elapsed = time.tv_usec - start_time;
}
yield(my_pid);
iterations--;
}
unregister(my_pid);
return 0;
}
int main(int argc, char** argv) {
if (argc != 2) {
fprintf(stderr, "usage: %s <size of working set in 4K pages>\n", *argv);
return 1;
}
const long ws_pages = strtol(argv[1], NULL, 10);
if (ws_pages < 0) {
fprintf(stderr, "Invalid usage: working set size must be positive\n");
return 1;
}
const int iterations = get_iterations(ws_pages);
struct timespec ts;
long long unsigned memset_time = 0;
if (ws_pages) {
void* buf = malloc(ws_pages * 4096);
memset_time = time_ns(&ts);
for (int i = 0; i < iterations; i++) {
memset(buf, i, ws_pages * 4096);
}
memset_time = time_ns(&ts) - memset_time;
printf("%i memset on %4liK in %10lluns (%.1fns/page)\n",
iterations, ws_pages * 4, memset_time,
(memset_time / ((float) ws_pages * iterations)));
free(buf);
}
const int shm_id = shmget(IPC_PRIVATE, (ws_pages + 1) * 4096,
IPC_CREAT | 0666);
const pid_t other = fork();
int* futex = shmat(shm_id, NULL, 0);
void* ws = ((char *) futex) + 4096;
*futex = 0xA;
if (other == 0) {
for (int i = 0; i < iterations; i++) {
sched_yield();
while (syscall(SYS_futex, futex, FUTEX_WAIT, 0xA, NULL, NULL, 42)) {
// retry
sched_yield();
}
*futex = 0xB;
if (ws_pages) {
memset(ws, i, ws_pages * 4096);
}
while (!syscall(SYS_futex, futex, FUTEX_WAKE, 1, NULL, NULL, 42)) {
// retry
sched_yield();
}
}
return 0;
}
const long long unsigned start_ns = time_ns(&ts);
for (int i = 0; i < iterations; i++) {
*futex = 0xA;
if (ws_pages) {
memset(ws, i, ws_pages * 4096);
}
while (!syscall(SYS_futex, futex, FUTEX_WAKE, 1, NULL, NULL, 42)) {
// retry
sched_yield();
}
sched_yield();
while (syscall(SYS_futex, futex, FUTEX_WAIT, 0xB, NULL, NULL, 42)) {
// retry
sched_yield();
}
}
const long long unsigned delta = time_ns(&ts) - start_ns - memset_time * 2;
const int nswitches = iterations * 4;
printf("%i process context switches (wss:%4liK) in %12lluns (%.1fns/ctxsw)\n",
nswitches, ws_pages * 4, delta, (delta / (float) nswitches));
wait(futex);
return 0;
}
