218c4e68c1
Rather than using linuxapp and bsdapp everywhere, we can change things to use the, more readable, terms "linux" and "freebsd" in our build configs. Rather than renaming the configs we can just duplicate the existing ones with the new names using symlinks, and use the new names exclusively internally. ["make showconfigs" also only shows the new names to keep the list short] The result is that backward compatibility is kept fully but any new builds or development can be done using the newer names, i.e. both "make config T=x86_64-native-linuxapp-gcc" and "T=x86_64-native-linux-gcc" work. Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
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3.2 KiB
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97 lines
3.2 KiB
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.. SPDX-License-Identifier: BSD-3-Clause
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Copyright(c) 2010-2014 Intel Corporation.
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Profile Your Application
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========================
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The following sections describe methods of profiling DPDK applications on
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different architectures.
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Profiling on x86
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----------------
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Intel processors provide performance counters to monitor events.
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Some tools provided by Intel, such as Intel® VTune™ Amplifier, can be used
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to profile and benchmark an application.
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See the *VTune Performance Analyzer Essentials* publication from Intel Press for more information.
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For a DPDK application, this can be done in a Linux* application environment only.
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The main situations that should be monitored through event counters are:
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* Cache misses
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* Branch mis-predicts
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* DTLB misses
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* Long latency instructions and exceptions
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Refer to the
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`Intel Performance Analysis Guide <http://software.intel.com/sites/products/collateral/hpc/vtune/performance_analysis_guide.pdf>`_
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for details about application profiling.
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Profiling with VTune
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~~~~~~~~~~~~~~~~~~~~
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To allow VTune attaching to the DPDK application, reconfigure and recompile
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the DPDK with ``CONFIG_RTE_ETHDEV_RXTX_CALLBACKS`` and
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``CONFIG_RTE_ETHDEV_PROFILE_WITH_VTUNE`` enabled.
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Profiling on ARM64
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------------------
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Using Linux perf
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~~~~~~~~~~~~~~~~
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The ARM64 architecture provide performance counters to monitor events. The
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Linux ``perf`` tool can be used to profile and benchmark an application. In
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addition to the standard events, ``perf`` can be used to profile arm64
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specific PMU (Performance Monitor Unit) events through raw events (``-e``
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``-rXX``).
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For more derails refer to the
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`ARM64 specific PMU events enumeration <http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.100095_0002_04_en/way1382543438508.html>`_.
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High-resolution cycle counter
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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The default ``cntvct_el0`` based ``rte_rdtsc()`` provides a portable means to
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get a wall clock counter in user space. Typically it runs at <= 100MHz.
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The alternative method to enable ``rte_rdtsc()`` for a high resolution wall
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clock counter is through the armv8 PMU subsystem. The PMU cycle counter runs
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at CPU frequency. However, access to the PMU cycle counter from user space is
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not enabled by default in the arm64 linux kernel. It is possible to enable
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cycle counter for user space access by configuring the PMU from the privileged
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mode (kernel space).
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By default the ``rte_rdtsc()`` implementation uses a portable ``cntvct_el0``
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scheme. Application can choose the PMU based implementation with
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``CONFIG_RTE_ARM_EAL_RDTSC_USE_PMU``.
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The example below shows the steps to configure the PMU based cycle counter on
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an armv8 machine.
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.. code-block:: console
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git clone https://github.com/jerinjacobk/armv8_pmu_cycle_counter_el0
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cd armv8_pmu_cycle_counter_el0
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make
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sudo insmod pmu_el0_cycle_counter.ko
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cd $DPDK_DIR
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make config T=arm64-armv8a-linux-gcc
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echo "CONFIG_RTE_ARM_EAL_RDTSC_USE_PMU=y" >> build/.config
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make
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.. warning::
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The PMU based scheme is useful for high accuracy performance profiling with
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``rte_rdtsc()``. However, this method can not be used in conjunction with
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Linux userspace profiling tools like ``perf`` as this scheme alters the PMU
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registers state.
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