On 04/04, Thomas Gleixner wrote:
IOW, we cannot test this reliably at all with the current approach.
Agreed!
So how about a REALLY SIMPLE test-case below?
Lacks error checking, should be updated to match tools/testing/selftests.
Without commit bcb7ee79029dca assert(sig_cnt > SIG_CNT) fails, the very 1st tick wakes the leader up.
With that commit it doesn't fail.
Oleg.
#include <stdio.h> #include <unistd.h> #include <signal.h> #include <pthread.h> #include <time.h> #include <assert.h>
#define SIG_CNT 100 static volatile int sig_cnt;
static void alarm_func(int sig) { ++sig_cnt; }
static void *thread_func(void *arg) { // one second before the 1st tick to ensure the leader sleeps struct itimerspec val = { .it_value.tv_sec = 1, .it_value.tv_nsec = 0, .it_interval.tv_sec = 0, .it_interval.tv_nsec = 1000 * 1000, }; timer_t id;
timer_create(CLOCK_PROCESS_CPUTIME_ID, NULL, &id); timer_settime(id, 0, &val, NULL);
while (sig_cnt < SIG_CNT) ;
// wake up the leader kill(getpid(), SIGALRM);
return NULL; }
int main(void) { pthread_t thread;
signal(SIGALRM, alarm_func);
pthread_create(&thread, NULL, thread_func, NULL);
pause();
assert(sig_cnt > SIG_CNT); // likely SIG_CNT + 1
return 0; }