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Commit 05e7ff7d authored Sep 11, 2009 by Heiko Carstens Committed by Martin Schwidefsky Sep 11, 2009

[S390] introduce get_clock_monotonic



Introduce get_clock_monotonic() function which can be used to get a
(fast) timestamp. Resolution is the same as for get_clock(). The
only difference is that the timestamps are monotonic and don't jump
backward or forward.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

parent ca99dab0

arch/s390/include/asm/timex.h

+14 −0

Original line number	Diff line number	Diff line
		@@ -90,4 +90,18 @@ unsigned long long monotonic_clock(void);

		extern u64 sched_clock_base_cc;

		/**
		* get_clock_monotonic - returns current time in clock rate units
		*
		* The caller must ensure that preemption is disabled.
		* The clock and sched_clock_base get changed via stop_machine.
		* Therefore preemption must be disabled when calling this
		* function, otherwise the returned value is not guaranteed to
		* be monotonic.
		*/
		static inline unsigned long long get_clock_monotonic(void)
		{
		return get_clock_xt() - sched_clock_base_cc;
		}

		#endif

arch/s390/kernel/time.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -60,6 +60,7 @@
		#define TICK_SIZE tick

		u64 sched_clock_base_cc = -1; /* Force to data section. */
		EXPORT_SYMBOL_GPL(sched_clock_base_cc);

		static DEFINE_PER_CPU(struct clock_event_device, comparators);

		@@ -68,7 +69,7 @@ static DEFINE_PER_CPU(struct clock_event_device, comparators);
		*/
		unsigned long long notrace sched_clock(void)
		{
		return ((get_clock_xt() - sched_clock_base_cc) * 125) >> 9;
		return (get_clock_monotonic() * 125) >> 9;
		}

		/*