Messages in this thread Patch in this message | | | Date | Wed, 07 Dec 2005 22:13:01 +0000 | From | Shailabh Nagar <> | Subject | [RFC][Patch 1/5] nanosecond timestamps and diffs |
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Add kernel utility functions for - nanosecond resolution timestamps, adjusted for lost ticks - interval (diff) between two such timestamps, in nanoseconds, adjusting for overflow
The timestamp part of this patch is identical to the one proposed by Matt Helsley (as part of adding timestamps to process event connectors) http://www.uwsg.indiana.edu/hypermail/linux/kernel/0512.0/1373.html
Signed-off-by: Shailabh Nagar <nagar@watson.ibm.com>
include/linux/time.h | 16 ++++++++++++++++ kernel/time.c | 22 ++++++++++++++++++++++ 2 files changed, 38 insertions(+)
Index: linux-2.6.15-rc5/include/linux/time.h =================================================================== --- linux-2.6.15-rc5.orig/include/linux/time.h +++ linux-2.6.15-rc5/include/linux/time.h @@ -95,6 +95,7 @@ struct itimerval; extern int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue); extern int do_getitimer(int which, struct itimerval *value); extern void getnstimeofday (struct timespec *tv); +extern void getnstimestamp(struct timespec *ts);
extern struct timespec timespec_trunc(struct timespec t, unsigned gran);
@@ -113,6 +114,21 @@ set_normalized_timespec (struct timespec ts->tv_nsec = nsec; }
+/* + * timespec_nsdiff - Return difference of two timestamps in nanoseconds + * In the rare case of @end being earlier than @start, return zero + */ +static inline unsigned long long +timespec_nsdiff(struct timespec *start, struct timespec *end) +{ + long long ret; + + ret = end->tv_sec*(1000000000) + end->tv_nsec; + ret -= start->tv_sec*(1000000000) + start->tv_nsec; + if (ret < 0) + return 0; + return ret; +} #endif /* __KERNEL__ */
#define NFDBITS __NFDBITS Index: linux-2.6.15-rc5/kernel/time.c =================================================================== --- linux-2.6.15-rc5.orig/kernel/time.c +++ linux-2.6.15-rc5/kernel/time.c @@ -561,6 +561,28 @@ void getnstimeofday(struct timespec *tv) EXPORT_SYMBOL_GPL(getnstimeofday); #endif
+void getnstimestamp(struct timespec *ts) +{ + unsigned int seq; + struct timespec wall2mono; + + /* synchronize with settimeofday() changes */ + do { + seq = read_seqbegin(&xtime_lock); + getnstimeofday(ts); + wall2mono = wall_to_monotonic; + } while(unlikely(read_seqretry(&xtime_lock, seq))); + + /* adjust to monotonicaly-increasing values */ + ts->tv_sec += wall2mono.tv_sec; + ts->tv_nsec += wall2mono.tv_nsec; + while (unlikely(ts->tv_nsec >= NSEC_PER_SEC)) { + ts->tv_nsec -= NSEC_PER_SEC; + ts->tv_sec++; + } +} +EXPORT_SYMBOL_GPL(getnstimestamp); + #if (BITS_PER_LONG < 64) u64 get_jiffies_64(void) { - 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/
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