#include <sys/select.h>
#include <errno.h>
#include <stdio.h>
#include <time.h>
int
main(void)
{
        struct timespec dts, ets, sts, ts;
        for (;;) {
                clock_gettime(CLOCK_MONOTONIC, &sts);   
#ifdef PSELECT
                ts.tv_sec = 0;
                ts.tv_nsec = 250000000;
                if (pselect(0, NULL, NULL, NULL, &ts, NULL) == -1
                    && errno == EINTR)
                        continue;
#else
                struct timeval tv;
                tv.tv_sec = 0;
                tv.tv_usec = 250000;
                if (select(0, NULL, NULL, NULL, &tv) == -1 && errno == EINTR)
                        continue;
                ts.tv_nsec = tv.tv_usec * 1000;
#endif
                clock_gettime(CLOCK_MONOTONIC, &ets);   
                timespecsub(&ets, &sts, &dts);
                if (dts.tv_nsec < 200000000) {
                        fprintf(stderr, "too little sleep r=%d s=%d\n",
                                dts.tv_nsec, ts.tv_nsec);
                }
        }
        return 0;
}