[PATCH] perf docu: Add description for stderr

From: Thomas Richter
Date: Mon May 13 2019 - 04:06:06 EST

Perf report displays recorded data on the screen and emits
warnings and debug messages in the status line (last one on screen).
Perf also supports the possibility to write all debug messages
to stderr (instead of writing them to the status line).
This is achieved with the following command:

# ./perf --debug stderr=1 report -vvvvv -i ~/fast.data 2>/tmp/2
# ll /tmp/2
-rw-rw-r-- 1 tmricht tmricht 5420835 May 7 13:46 /tmp/2

The usage of variable stderr=1 is not documented, so add it
to the perf man page.

Signed-off-by: Thomas Richter <tmricht@xxxxxxxxxxxxx>
tools/perf/Documentation/perf.txt | 2 ++
1 file changed, 2 insertions(+)

diff --git a/tools/perf/Documentation/perf.txt b/tools/perf/Documentation/perf.txt
index 864e37597252..401f0ed67439 100644
--- a/tools/perf/Documentation/perf.txt
+++ b/tools/perf/Documentation/perf.txt
@@ -22,6 +22,8 @@ OPTIONS
verbose - general debug messages
ordered-events - ordered events object debug messages
data-convert - data convert command debug messages
+ stderr - write debug output (option -v) to stderr
+ in browser mode

Setup buildid cache directory. It has higher priority than