[dpdk-dev,v2] doc: add how to enable empty cycles profiling
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Commit Message
From: Ilia Kurakin <ilia.kurakin@intel.com>
Programmers Guide: section "Profile Your Application" updated
with how to enable ITT tasks collection. Based on patch:
http://dpdk.org/dev/patchwork/patch/27158/
Signed-off-by: Ilia Kurakin <ilia.kurakin@intel.com>
---
-V2 change:
Fixes due to review
doc/guides/prog_guide/profile_app.rst | 37 ++++++++++++++++++++++++++++++++++-
1 file changed, 36 insertions(+), 1 deletion(-)
Comments
> -----Original Message-----
> From: Kurakin, Ilia
> Sent: Wednesday, July 26, 2017 4:20 PM
> To: dev@dpdk.org
> Cc: jerin.jacob@caviumnetworks.com; Mcnamara, John
> <john.mcnamara@intel.com>; Galanov, Dmitry <dmitry.galanov@intel.com>;
> Kurakin, Ilia <ilia.kurakin@intel.com>
> Subject: [PATCH v2] doc: add how to enable empty cycles profiling
>
> From: Ilia Kurakin <ilia.kurakin@intel.com>
>
> Programmers Guide: section "Profile Your Application" updated with how to
> enable ITT tasks collection. Based on patch:
> http://dpdk.org/dev/patchwork/patch/27158/
>
> Signed-off-by: Ilia Kurakin <ilia.kurakin@intel.com>
Acked-by: John McNamara <john.mcnamara@intel.com>
@@ -39,7 +39,8 @@ Profiling on x86
----------------
Intel processors provide performance counters to monitor events.
-Some tools provided by Intel, such as VTune, can be used to profile and benchmark an application.
+Some tools provided by Intel, such as Intel® VTune™ Amplifier, can be used
+to profile and benchmark an application.
See the *VTune Performance Analyzer Essentials* publication from Intel Press for more information.
For a DPDK application, this can be done in a Linux* application environment only.
@@ -59,6 +60,40 @@ Refer to the
for details about application profiling.
+VTune ITT
+~~~~~~~~~
+
+Iterations that yielded no RX packets (wasted loop iterations) can be analyzed
+using VTune Amplifier. This profiling employs the
+`Instrumentation and Tracing Technology (ITT) API
+<https://software.intel.com/en-us/node/544195>`_
+feature of VTune Amplifier and requires only reconfiguring the DPDK library,
+no changes in a DPDK application are needed.
+
+To trace wasted iterations on RX queues, first reconfigure DPDK with
+``CONFIG_RTE_ETHDEV_RXTX_CALLBACKS`` and
+``CONFIG_RTE_ETHDEV_PROFILE_ITT_WASTED_RX_ITERATIONS`` enabled.
+
+Then rebuild DPDK, specifying paths to the ITT header and library, which can
+be found in any VTune Amplifier distribution in the *include* and *lib*
+directories respectively:
+
+.. code-block:: console
+
+ make EXTRA_CFLAGS=-I<path to ittnotify.h> \
+ EXTRA_LDLIBS="-L<path to libittnotify.a> -littnotify"
+
+Finally, to see wasted iterations in your performance analysis results,
+select the *"Analyze user tasks, events, and counters"* checkbox in the
+*"Analysis Type"* tab when configuring analysis via VTune Amplifier GUI.
+Alternatively, when running VTune Amplifier via command line, specify
+``-knob enable-user-tasks=true`` option.
+
+Collected regions of wasted iterations will be marked on VTune Amplifier's
+timeline as ITT tasks. These ITT tasks have predefined names, containing
+Ethernet device and RX queue identifiers.
+
+
Profiling on ARM64
------------------