-.. BSD LICENSE
- Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
- All rights reserved.
-
- Redistribution and use in source and binary forms, with or without
- modification, are permitted provided that the following conditions
- are met:
-
- * Redistributions of source code must retain the above copyright
- notice, this list of conditions and the following disclaimer.
- * Redistributions in binary form must reproduce the above copyright
- notice, this list of conditions and the following disclaimer in
- the documentation and/or other materials provided with the
- distribution.
- * Neither the name of Intel Corporation nor the names of its
- contributors may be used to endorse or promote products derived
- from this software without specific prior written permission.
-
- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+.. SPDX-License-Identifier: BSD-3-Clause
+ Copyright(c) 2010-2014 Intel Corporation.
Profile Your Application
========================
for details about application profiling.
-Empty cycles tracing
+Profiling with VTune
~~~~~~~~~~~~~~~~~~~~
-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:
+To allow VTune attaching to the DPDK application, reconfigure a DPDK build
+folder by passing ``-Dc_args=-DRTE_ETHDEV_PROFILE_WITH_VTUNE`` meson option
+and recompile the DPDK:
.. 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.
+ meson build
+ meson configure build -Dc_args=-DRTE_ETHDEV_PROFILE_WITH_VTUNE
+ ninja -C build
Profiling on ARM64
`ARM64 specific PMU events enumeration <http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.100095_0002_04_en/way1382543438508.html>`_.
-High-resolution cycle counter
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Low-resolution generic counter
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The default ``cntvct_el0`` based ``rte_rdtsc()`` provides a portable means to
-get a wall clock counter in user space. Typically it runs at <= 100MHz.
+get a wall clock counter in user space. Typically it runs at a lower clock frequency than the CPU clock frequency.
+Cycles counted using this method should be scaled to CPU clock frequency.
+
+
+High-resolution cycle counter
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The alternative method to enable ``rte_rdtsc()`` for a high resolution wall
-clock counter is through the armv8 PMU subsystem. The PMU cycle counter runs
+clock counter is through the ARMv8 PMU subsystem. The PMU cycle counter runs
at CPU frequency. However, access to the PMU cycle counter from user space is
not enabled by default in the arm64 linux kernel. It is possible to enable
cycle counter for user space access by configuring the PMU from the privileged
mode (kernel space).
By default the ``rte_rdtsc()`` implementation uses a portable ``cntvct_el0``
-scheme. Application can choose the PMU based implementation with
-``CONFIG_RTE_ARM_EAL_RDTSC_USE_PMU``.
+scheme.
The example below shows the steps to configure the PMU based cycle counter on
-an armv8 machine.
+an ARMv8 machine.
.. code-block:: console
cd armv8_pmu_cycle_counter_el0
make
sudo insmod pmu_el0_cycle_counter.ko
- cd $DPDK_DIR
- make config T=arm64-armv8a-linuxapp-gcc
- echo "CONFIG_RTE_ARM_EAL_RDTSC_USE_PMU=y" >> build/.config
- make
+
+Please refer to :doc:`../linux_gsg/build_dpdk` for details on compiling DPDK with meson.
.. warning::
git.droids-corp.org / dpdk.git / blobdiff