The usage of proftool in docs is incorrect. If proftool is used without '-o' argument, it will show the usage like following

$ ./sandbox/tools/proftool -m sandbox/System.map -t trace -f funcgraph dump-ftrace >trace.dat Must provide trace data, System.map file and output file Usage: proftool [-cmtv] <cmd> <profdata>

Change '>' to '-o' to fix it.

Signed-off-by: Puhan Zhou puh4n.zhou@gmail.com --- doc/develop/trace.rst | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/doc/develop/trace.rst b/doc/develop/trace.rst index 9bbe1345d2..546862020b 100644 --- a/doc/develop/trace.rst +++ b/doc/develop/trace.rst @@ -139,7 +139,7 @@ There is a -f option available to select a function graph:

.. code-block:: console

- $ ./sandbox/tools/proftool -m sandbox/System.map -t trace -f funcgraph dump-ftrace >trace.dat + $ ./sandbox/tools/proftool -m sandbox/System.map -t trace -f funcgraph dump-ftrace -o trace.dat

Again, you can use kernelshark or trace-cmd to look at the output. In this case you will see the time taken by each function shown against its exit record. @@ -171,7 +171,7 @@ command:

.. code-block:: console

- $ ./sandbox/tools/proftool -m sandbox/System.map -t trace dump-flamegraph >trace.fg + $ ./sandbox/tools/proftool -m sandbox/System.map -t trace dump-flamegraph -o trace.fg $ flamegraph.pl trace.fg >trace.svg

You can load the .svg file into a viewer. If you use Chrome (and some other @@ -191,7 +191,7 @@ spend in each call stack:

.. code-block:: console

- $ ./sandbox/tools/proftool -m sandbox/System.map -t trace dump-flamegraph -f timing >trace.fg + $ ./sandbox/tools/proftool -m sandbox/System.map -t trace dump-flamegraph -f timing -o trace.fg $ flamegraph.pl trace.fg >trace.svg

Note that trace collection does slow down execution so the timings will be