1 files changed, 36 insertions, 2 deletions

diff --git a/tools/perf/Documentation/perf-timechart.txt b/tools/perf/Documentation/perf-timechart.txt
index 5e0f986dff38..df98d1c82688 100644
--- a/tools/perf/Documentation/perf-timechart.txt
+++ b/tools/perf/Documentation/perf-timechart.txt
@@ -15,10 +15,20 @@ DESCRIPTION
 There are two variants of perf timechart:
 
   'perf timechart record <command>' to record the system level events
-  of an arbitrary workload.
+  of an arbitrary workload. By default timechart records only scheduler
+  and CPU events (task switches, running times, CPU power states, etc),
+  but it's possible to record IO (disk, network) activity using -I argument.
 
   'perf timechart' to turn a trace into a Scalable Vector Graphics file,
-  that can be viewed with popular SVG viewers such as 'Inkscape'.
+  that can be viewed with popular SVG viewers such as 'Inkscape'. Depending
+  on the events in the perf.data file, timechart will contain scheduler/cpu
+  events or IO events.
+
+  In IO mode, every bar has two charts: upper and lower.
+  Upper bar shows incoming events (disk reads, ingress network packets).
+  Lower bar shows outgoing events (disk writes, egress network packets).
+  There are also poll bars which show how much time application spent
+  in poll/epoll/select syscalls.
 
 TIMECHART OPTIONS
 -----------------
@@ -54,6 +64,19 @@ TIMECHART OPTIONS
         duration or tasks with given name. If number is given it's interpreted
         as number of nanoseconds. If non-numeric string is given it's
         interpreted as task name.
+--io-skip-eagain::
+        Don't draw EAGAIN IO events.
+--io-min-time=<nsecs>::
+        Draw small events as if they lasted min-time. Useful when you need
+        to see very small and fast IO. It's possible to specify ms or us
+        suffix to specify time in milliseconds or microseconds.
+        Default value is 1ms.
+--io-merge-dist=<nsecs>::
+        Merge events that are merge-dist nanoseconds apart.
+        Reduces number of figures on the SVG and makes it more render-friendly.
+        It's possible to specify ms or us suffix to specify time in
+        milliseconds or microseconds.
+        Default value is 1us.
 
 RECORD OPTIONS
 --------------
@@ -63,6 +86,9 @@ RECORD OPTIONS
 -T::
 --tasks-only::
         Record only tasks-related events
+-I::
+--io-only::
+        Record only io-related events
 -g::
 --callchain::
         Do call-graph (stack chain/backtrace) recording
@@ -87,6 +113,14 @@ Record system-wide timechart:
 
   $ perf timechart --highlight gcc
 
+Record system-wide IO events:
+
+  $ perf timechart record -I
+
+  then generate timechart:
+
+  $ perf timechart
+
 SEE ALSO
 --------
 linkperf:perf-record[1]