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authorSteven Rostedt (Red Hat) <rostedt@goodmis.org>2013-03-14 13:13:45 -0400
committerSteven Rostedt <rostedt@goodmis.org>2013-03-15 00:36:09 -0400
commit8aacf017b065a805d27467843490c976835eb4a5 (patch)
tree3e3ee23502cf2cc6d02baa1f7625b1ef16611eda
parent328df4759c03e2c3e7429cc6cb0e180c38f32063 (diff)
tracing: Add "uptime" trace clock that uses jiffies
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>
-rw-r--r--include/linux/trace_clock.h1
-rw-r--r--kernel/trace/trace.c1
-rw-r--r--kernel/trace/trace_clock.c10
3 files changed, 12 insertions, 0 deletions
diff --git a/include/linux/trace_clock.h b/include/linux/trace_clock.h
index d563f37e1a1d..1d7ca2739272 100644
--- a/include/linux/trace_clock.h
+++ b/include/linux/trace_clock.h
@@ -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);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index f90ca16afcf2..8eabfbb8003e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -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
};
diff --git a/kernel/trace/trace_clock.c b/kernel/trace/trace_clock.c
index aa8f5f48dae6..26dc348332b7 100644
--- a/kernel/trace/trace_clock.c
+++ b/kernel/trace/trace_clock.c
@@ -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