tracing: Add "uptime" trace clock that uses jiffies (8aacf017) · Commits · 戴 / test

Add a simple trace clock called "uptime" for those that are interested in the uptime of the trace. It uses jiffies as that's the safest method, as other uptime clocks grab seq locks, which could cause a deadlock if taken from an event or function tracer. Requested-by:

Mauro Carvalho Chehab <mchehab@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by:

Steven Rostedt <rostedt@goodmis.org>

include/linux/trace_clock.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -16,6 +16,7 @@

		extern u64 notrace trace_clock_local(void);
		extern u64 notrace trace_clock(void);
		extern u64 notrace trace_clock_jiffies(void);
		extern u64 notrace trace_clock_global(void);
		extern u64 notrace trace_clock_counter(void);

kernel/trace/trace.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -647,6 +647,7 @@ static struct {
		{ trace_clock_local, "local", 1 },
		{ trace_clock_global, "global", 1 },
		{ trace_clock_counter, "counter", 0 },
		{ trace_clock_jiffies, "uptime", 1 },
		ARCH_TRACE_CLOCKS
		};

kernel/trace/trace_clock.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -57,6 +57,16 @@ u64 notrace trace_clock(void)
		return local_clock();
		}

		/*
		* trace_jiffy_clock(): Simply use jiffies as a clock counter.
		*/
		u64 notrace trace_clock_jiffies(void)
		{
		u64 jiffy = jiffies - INITIAL_JIFFIES;

		/* Return nsecs */
		return (u64)jiffies_to_usecs(jiffy) * 1000ULL;
		}

		/*
		* trace_clock_global(): special globally coherent trace clock

Admin message