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31 Profile Your Application
32 ========================
34 The following sections describe methods of profiling DPDK applications on
35 different architectures.
41 Intel processors provide performance counters to monitor events.
42 Some tools provided by Intel, such as VTune, can be used to profile and benchmark an application.
43 See the *VTune Performance Analyzer Essentials* publication from Intel Press for more information.
45 For a DPDK application, this can be done in a Linux* application environment only.
47 The main situations that should be monitored through event counters are:
55 * Long latency instructions and exceptions
58 `Intel Performance Analysis Guide <http://software.intel.com/sites/products/collateral/hpc/vtune/performance_analysis_guide.pdf>`_
59 for details about application profiling.
68 The ARM64 architecture provide performance counters to monitor events. The
69 Linux ``perf`` tool can be used to profile and benchmark an application. In
70 addition to the standard events, ``perf`` can be used to profile arm64
71 specific PMU (Performance Monitor Unit) events through raw events (``-e``
74 For more derails refer to the
75 `ARM64 specific PMU events enumeration <http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.100095_0002_04_en/way1382543438508.html>`_.
78 High-resolution cycle counter
79 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
81 The default ``cntvct_el0`` based ``rte_rdtsc()`` provides a portable means to
82 get a wall clock counter in user space. Typically it runs at <= 100MHz.
84 The alternative method to enable ``rte_rdtsc()`` for a high resolution wall
85 clock counter is through the armv8 PMU subsystem. The PMU cycle counter runs
86 at CPU frequency. However, access to the PMU cycle counter from user space is
87 not enabled by default in the arm64 linux kernel. It is possible to enable
88 cycle counter for user space access by configuring the PMU from the privileged
91 By default the ``rte_rdtsc()`` implementation uses a portable ``cntvct_el0``
92 scheme. Application can choose the PMU based implementation with
93 ``CONFIG_RTE_ARM_EAL_RDTSC_USE_PMU``.
95 The example below shows the steps to configure the PMU based cycle counter on
98 .. code-block:: console
100 git clone https://github.com/jerinjacobk/armv8_pmu_cycle_counter_el0
101 cd armv8_pmu_cycle_counter_el0
103 sudo insmod pmu_el0_cycle_counter.ko
105 make config T=arm64-armv8a-linuxapp-gcc
106 echo "CONFIG_RTE_ARM_EAL_RDTSC_USE_PMU=y" >> build/.config
111 The PMU based scheme is useful for high accuracy performance profiling with
112 ``rte_rdtsc()``. However, this method can not be used in conjunction with
113 Linux userspace profiling tools like ``perf`` as this scheme alters the PMU