diff options
| author | Christoph Lameter <clameter@sgi.com> | 2004-08-22 22:47:16 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2004-08-22 22:47:16 -0700 |
| commit | b9cbc585eda36c84edbf05c0e83e3bf950ff45fa (patch) | |
| tree | b23b0f8016bcfc8e256f5a61fa20803ba4ffada1 /kernel/time.c | |
| parent | 346ed9c13aab9be890a8bd52d06fd6761876bb85 (diff) | |
[PATCH] gettimeofday nanoseconds patch
This issue was discussed on lkml and linux-ia64. The patch introduces
"getnstimeofday" and removes all the code scaling gettimeofday to
nanoseoncs. It makes it possible for the posix-timer functions to return
higher accuracy.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel/time.c')
| -rw-r--r-- | kernel/time.c | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/kernel/time.c b/kernel/time.c index 68c22f2bf452..b0bdef2b7f20 100644 --- a/kernel/time.c +++ b/kernel/time.c @@ -22,6 +22,9 @@ * "A Kernel Model for Precision Timekeeping" by Dave Mills * Allow time_constant larger than MAXTC(6) for NTP v4 (MAXTC == 10) * (Even though the technical memorandum forbids it) + * 2004-07-14 Christoph Lameter + * Added getnstimeofday to allow the posix timer functions to return + * with nanosecond accuracy */ #include <linux/module.h> @@ -421,6 +424,41 @@ struct timespec current_kernel_time(void) EXPORT_SYMBOL(current_kernel_time); +#ifdef CONFIG_TIME_INTERPOLATION +void getnstimeofday (struct timespec *tv) +{ + unsigned long seq,sec,nsec; + + do { + seq = read_seqbegin(&xtime_lock); + sec = xtime.tv_sec; + nsec = xtime.tv_nsec+time_interpolator_get_offset(); + } while (unlikely(read_seqretry(&xtime_lock, seq))); + + while (unlikely(nsec >= NSEC_PER_SEC)) { + nsec -= NSEC_PER_SEC; + ++sec; + } + tv->tv_sec = sec; + tv->tv_nsec = nsec; +} +#else +/* + * Simulate gettimeofday using do_gettimeofday which only allows a timeval + * and therefore only yields usec accuracy + */ +void getnstimeofday(struct timespec *tv) +{ + struct timeval x; + + do_gettimeofday(&x); + tv->tv_sec = x.tv_sec; + tv->tv_nsec = x.tv_usec * NSEC_PER_USEC; +} +#endif + +EXPORT_SYMBOL(getnstimeofday); + #if (BITS_PER_LONG < 64) u64 get_jiffies_64(void) { |