diff options
| -rw-r--r-- | arch/um/os-Linux/time.c | 54 |
1 files changed, 51 insertions, 3 deletions
diff --git a/arch/um/os-Linux/time.c b/arch/um/os-Linux/time.c index e34e1effe0f5..ef02d941c2ad 100644 --- a/arch/um/os-Linux/time.c +++ b/arch/um/os-Linux/time.c @@ -59,7 +59,7 @@ long long disable_timer(void) { struct itimerval time = ((struct itimerval) { { 0, 0 }, { 0, 0 } }); - if(setitimer(ITIMER_VIRTUAL, &time, &time) < 0) + if (setitimer(ITIMER_VIRTUAL, &time, &time) < 0) printk(UM_KERN_ERR "disable_timer - setitimer failed, " "errno = %d\n", errno); @@ -74,13 +74,61 @@ long long os_nsecs(void) return timeval_to_ns(&tv); } +#ifdef UML_CONFIG_NO_HZ +static int after_sleep_interval(struct timespec *ts) +{ +} +#else +static inline long long timespec_to_us(const struct timespec *ts) +{ + return ((long long) ts->tv_sec * UM_USEC_PER_SEC) + + ts->tv_nsec / UM_NSEC_PER_USEC; +} + +static int after_sleep_interval(struct timespec *ts) +{ + int usec = UM_USEC_PER_SEC / UM_HZ; + long long start_usecs = timespec_to_us(ts); + struct timeval tv; + struct itimerval interval; + + /* + * It seems that rounding can increase the value returned from + * setitimer to larger than the one passed in. Over time, + * this will cause the remaining time to be greater than the + * tick interval. If this happens, then just reduce the first + * tick to the interval value. + */ + if (start_usecs > usec) + start_usecs = usec; + tv = ((struct timeval) { .tv_sec = start_usecs / UM_USEC_PER_SEC, + .tv_usec = start_usecs % UM_USEC_PER_SEC }); + interval = ((struct itimerval) { { 0, usec }, tv }); + + if (setitimer(ITIMER_VIRTUAL, &interval, NULL) == -1) + return -errno; + + return 0; +} +#endif + extern void alarm_handler(int sig, struct sigcontext *sc); void idle_sleep(unsigned long long nsecs) { - struct timespec ts = { .tv_sec = nsecs / UM_NSEC_PER_SEC, - .tv_nsec = nsecs % UM_NSEC_PER_SEC }; + struct timespec ts; + + /* + * nsecs can come in as zero, in which case, this starts a + * busy loop. To prevent this, reset nsecs to the tick + * interval if it is zero. + */ + if (nsecs == 0) + nsecs = UM_NSEC_PER_SEC / UM_HZ; + ts = ((struct timespec) { .tv_sec = nsecs / UM_NSEC_PER_SEC, + .tv_nsec = nsecs % UM_NSEC_PER_SEC }); if (nanosleep(&ts, &ts) == 0) alarm_handler(SIGVTALRM, NULL); + after_sleep_interval(&ts); } |