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Diffstat (limited to 'doc/guides/prog_guide/profile_app.rst')
| -rw-r--r-- | doc/guides/prog_guide/profile_app.rst | 37 |
1 files changed, 36 insertions, 1 deletions
diff --git a/doc/guides/prog_guide/profile_app.rst b/doc/guides/prog_guide/profile_app.rst index 54b546ac..ca1c91f6 100644 --- a/doc/guides/prog_guide/profile_app.rst +++ b/doc/guides/prog_guide/profile_app.rst @@ -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. +Empty cycles tracing +~~~~~~~~~~~~~~~~~~~~ + +Iterations that yielded no RX packets (empty cycles, wasted 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 ------------------ |