In article <3C05DC1D.7071FC6B@yahoo.com> you wrote:
> Greetings,
>
> For many of us, the kernel thread scheduling resolution is
> 10ms (see getitimer(2)). By adding 1 jiffy to the time to
> sleep in sys_nanosleep(), threads are sleeping 10ms too long.
> timespec_to_jiffies() does a good job at returning the
> appropriate number of jiffies to sleep. There is no need to
> add one for good measure.
Please take a look at:
http://www.kernel.org/pub/linux/kernel/people/andrea/kernels/v2.4/2.4.15aa1/00_nanosleep-5
instead.
Linus & Marcelo: any chance to get that into the tree? (patch is inlined below)
Christoph
-- Of course it doesn't work. We've performed a software upgrade.diff -urN 2.4.6pre6/include/linux/time.h nanosleep/include/linux/time.h --- 2.4.6pre6/include/linux/time.h Thu Jun 14 18:07:48 2001 +++ nanosleep/include/linux/time.h Thu Jun 28 11:47:14 2001 @@ -48,6 +48,27 @@ value->tv_sec = jiffies / HZ; } +static __inline__ int +timespec_before(struct timespec a, struct timespec b) +{ + if (a.tv_sec == b.tv_sec) + return a.tv_nsec < b.tv_nsec; + return a.tv_sec < b.tv_sec; +} + +/* computes `a - b' and write the result in `result', assumes `a >= b' */ +static inline void +timespec_less(struct timespec a, struct timespec b, struct timespec * result) +{ + if (a.tv_nsec < b.tv_nsec) + { + a.tv_sec--; + a.tv_nsec += 1000000000; + } + + result->tv_sec = a.tv_sec - b.tv_sec; + result->tv_nsec = a.tv_nsec - b.tv_nsec; +} /* Converts Gregorian date to seconds since 1970-01-01 00:00:00. * Assumes input in normal date format, i.e. 1980-12-31 23:59:59 @@ -89,6 +110,27 @@ time_t tv_sec; /* seconds */ suseconds_t tv_usec; /* microseconds */ }; + +/* computes `a - b' and write the result in `result', assumes `a >= b' */ +static inline void +timeval_less(struct timeval a, struct timeval b, struct timeval * result) +{ + if (a.tv_usec < b.tv_usec) + { + a.tv_sec--; + a.tv_usec += 1000000; + } + + result->tv_sec = a.tv_sec - b.tv_sec; + result->tv_usec = a.tv_usec - b.tv_usec; +} + +static __inline__ void +timeval_to_timespec(struct timeval tv, struct timespec * ts) +{ + ts->tv_sec = tv.tv_sec; + ts->tv_nsec = (long) tv.tv_usec * 1000; +} struct timezone { int tz_minuteswest; /* minutes west of Greenwich */ diff -urN 2.4.6pre6/kernel/timer.c nanosleep/kernel/timer.c --- 2.4.6pre6/kernel/timer.c Thu Jun 28 11:38:09 2001 +++ nanosleep/kernel/timer.c Thu Jun 28 11:48:47 2001 @@ -798,6 +798,7 @@ { struct timespec t; unsigned long expire; + struct timeval before, after; if(copy_from_user(&t, rqtp, sizeof(struct timespec))) return -EFAULT; @@ -822,11 +823,20 @@ expire = timespec_to_jiffies(&t) + (t.tv_sec || t.tv_nsec); current->state = TASK_INTERRUPTIBLE; + get_fast_time(&before); expire = schedule_timeout(expire); + get_fast_time(&after); if (expire) { if (rmtp) { - jiffies_to_timespec(expire, &t); + struct timespec elapsed; + + timeval_less(after, before, &after); + timeval_to_timespec(after, &elapsed); + if (timespec_before(elapsed, t)) + timespec_less(t, elapsed, &t); + else + t.tv_nsec = t.tv_sec = 0; if (copy_to_user(rmtp, &t, sizeof(struct timespec))) return -EFAULT; } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Fri Nov 30 2001 - 21:00:33 EST