ring-buffer: add api to allow a tracer to change clock source
This patch adds a new function called ring_buffer_set_clock that
allows a tracer to assign its own clock source to the buffer.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 8f89690..3be2f78 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -155,13 +155,6 @@
return nsec;
}
-cycle_t ftrace_now(int cpu)
-{
- u64 ts = ring_buffer_time_stamp(cpu);
- ring_buffer_normalize_time_stamp(cpu, &ts);
- return ts;
-}
-
/*
* The global_trace is the descriptor that holds the tracing
* buffers for the live tracing. For each CPU, it contains
@@ -178,6 +171,20 @@
static DEFINE_PER_CPU(struct trace_array_cpu, global_trace_cpu);
+cycle_t ftrace_now(int cpu)
+{
+ u64 ts;
+
+ /* Early boot up does not have a buffer yet */
+ if (!global_trace.buffer)
+ return trace_clock_local();
+
+ ts = ring_buffer_time_stamp(global_trace.buffer, cpu);
+ ring_buffer_normalize_time_stamp(global_trace.buffer, cpu, &ts);
+
+ return ts;
+}
+
/*
* The max_tr is used to snapshot the global_trace when a maximum
* latency is reached. Some tracers will use this to store a maximum