[PATCH] trace: Add documentation for mono and mono_raw trace clocks

[Joel Fernandes <joelaf@google.com>]

mono and mono_raw trace clocks access CLOCK_MONOTONIC and CLOCK_MONOTONIC_RAW
clocks for tracing purposes. Add documentation for the same.

Signed-off-by: Joel Fernandes <joelaf@google.com>
---
Steven,
I skipped adding docs for boot clock as that patch is still being discussed,
but please accept documentation for the other clocks you said were missing.
I will follow with the boot clock documentation at a later time. Thanks.

 Documentation/trace/ftrace.txt | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index 185c39f..32cc1ee 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -362,6 +362,14 @@ of ftrace. Here is a list of some of the key files:
 		  to correlate events across hypervisor/guest if
 		  tb_offset is known.
 
+	  mono: This uses the fast monotonic clock (CLOCK_MONOTONIC)
+		which is monotonic and is subject to NTP rate adjustments.
+
+	  mono_raw:
+		This is the raw monotonic clock (CLOCK_MONOTONIC_RAW)
+		which is montonic but is not subject to any rate adjustments
+		and ticks at the same rate as the hardware clocksource.
+
 	To set a clock, simply echo the clock name into this file.
 
 	  echo global > trace_clock
-- 
2.8.0.rc3.226.g39d4020