[dpdk-dev] [PATCH v9 4/4] doc/guides/sample_app_ug/l3_forward_power_man.rst: empty poll update

[Liang Ma <liang.j.ma@intel.com>]

Add empty poll mode command line example

ChangeLogs:
v9: update the document

Signed-off-by: Liang Ma <liang.j.ma@intel.com>
---
 doc/guides/sample_app_ug/l3_forward_power_man.rst | 69 +++++++++++++++++++++++
 1 file changed, 69 insertions(+)

diff --git a/doc/guides/sample_app_ug/l3_forward_power_man.rst b/doc/guides/sample_app_ug/l3_forward_power_man.rst
index 795a570..e44a11b 100644
--- a/doc/guides/sample_app_ug/l3_forward_power_man.rst
+++ b/doc/guides/sample_app_ug/l3_forward_power_man.rst
@@ -105,6 +105,8 @@ where,
 
 *   --no-numa: optional, disables numa awareness
 
+*   --empty-poll: Traffic Aware power management. See below for details
+
 See :doc:`l3_forward` for details.
 The L3fwd-power example reuses the L3fwd command line options.
 
@@ -362,3 +364,70 @@ The algorithm has the following sleeping behavior depending on the idle counter:
 If a thread polls multiple Rx queues and different queue returns different sleep duration values,
 the algorithm controls the sleep time in a conservative manner by sleeping for the least possible time
 in order to avoid a potential performance impact.
+
+Empty Poll Mode
+-------------------------
+Additionally, there is a traffic aware mode of operation called "Empty
+Poll" where the number of empty polls can be monitored to keep track
+of how busy the application is. Empty poll mode can be enabled by the
+command line option --empty-poll.
+
+See :doc:`Power Management<../prog_guide/power_man>` chapter in the DPDK Programmer's Guide for empty poll mode details.
+
+.. code-block:: console
+
+    ./l3fwd-power -l xxx   -n 4   -w 0000:xx:00.0 -w 0000:xx:00.1 -- -p 0x3 -P --config="(0,0,xx),(1,0,xx)" --empty-poll="0,0,0" -l 14 -m 9 -h 1
+
+Where,
+
+--empty-poll: Enable the empty poll mode instead of original algorithm
+
+--empty-poll="training_flag, med_threshold, high_threshold"
+
+* ``training_flag`` : optional, enable/disable training mode. Default value is 0. If the training_flag is set as 1(true), then the application will start in training mode and print out the trained threshold values. If the training_flag is set as 0(false), the application will start in normal mode, and will use either the default thresholds or those supplied on the command line. The trained threshold values are specific to the user’s system, may give a better power profile when compared to the default threshold values.
+
+* ``med_threshold`` : optional, sets the empty poll threshold of a modestly busy system state. If this is not supplied, the application will apply the default value of 350000.
+
+* ``high_threshold`` : optional, sets the empty poll threshold of a busy system state. If this is not supplied, the application will apply the default value of 580000.
+
+* -l : optional, set up the LOW power state frequency index
+
+* -m : optional, set up the MED power state frequency index
+
+* -h : optional, set up the HIGH power state frequency index
+
+Empty Poll Mode Example Usage
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+To initially obtain the ideal thresholds for the system, the training
+mode should be run first. This is achieved by running the l3fwd-power
+app with the training flag set to “1”, and the other parameters set to
+0.
+
+.. code-block:: console
+
+        ./examples/l3fwd-power/build/l3fwd-power -l 1-3 -- -p 0x0f --config="(0,0,2),(0,1,3)" --empty-poll "1,0,0" –P
+
+This will run the training algorithm for x seconds on each core (cores 2
+and 3), and then print out the recommended threshold values for those
+cores. The thresholds should be very similar for each core.
+
+.. code-block:: console
+
+        POWER: Bring up the Timer
+        POWER: set the power freq to MED
+        POWER: Low threshold is 230277
+        POWER: MED threshold is 335071
+        POWER: HIGH threshold is 523769
+        POWER: Training is Complete for 2
+        POWER: set the power freq to MED
+        POWER: Low threshold is 236814
+        POWER: MED threshold is 344567
+        POWER: HIGH threshold is 538580
+        POWER: Training is Complete for 3
+
+Once the values have been measured for a particular system, the app can
+then be started without the training mode so traffic can start immediately.
+
+.. code-block:: console
+
+        ./examples/l3fwd-power/build/l3fwd-power -l 1-3 -- -p 0x0f --config="(0,0,2),(0,1,3)" --empty-poll "0,340000,540000" –P
-- 
2.7.5