]>
Commit | Line | Data |
---|---|---|
11fdf7f2 TL |
1 | .. SPDX-License-Identifier: BSD-3-Clause |
2 | Copyright(c) 2010-2014 Intel Corporation. | |
7c673cae FG |
3 | |
4 | Profile Your Application | |
5 | ======================== | |
6 | ||
7 | The following sections describe methods of profiling DPDK applications on | |
8 | different architectures. | |
9 | ||
10 | ||
11 | Profiling on x86 | |
12 | ---------------- | |
13 | ||
14 | Intel processors provide performance counters to monitor events. | |
11fdf7f2 TL |
15 | Some tools provided by Intel, such as Intel® VTune™ Amplifier, can be used |
16 | to profile and benchmark an application. | |
7c673cae FG |
17 | See the *VTune Performance Analyzer Essentials* publication from Intel Press for more information. |
18 | ||
19 | For a DPDK application, this can be done in a Linux* application environment only. | |
20 | ||
21 | The main situations that should be monitored through event counters are: | |
22 | ||
23 | * Cache misses | |
24 | ||
25 | * Branch mis-predicts | |
26 | ||
27 | * DTLB misses | |
28 | ||
29 | * Long latency instructions and exceptions | |
30 | ||
31 | Refer to the | |
32 | `Intel Performance Analysis Guide <http://software.intel.com/sites/products/collateral/hpc/vtune/performance_analysis_guide.pdf>`_ | |
33 | for details about application profiling. | |
11fdf7f2 TL |
34 | |
35 | ||
9f95a23c | 36 | Profiling with VTune |
11fdf7f2 TL |
37 | ~~~~~~~~~~~~~~~~~~~~ |
38 | ||
9f95a23c TL |
39 | To allow VTune attaching to the DPDK application, reconfigure and recompile |
40 | the DPDK with ``CONFIG_RTE_ETHDEV_RXTX_CALLBACKS`` and | |
41 | ``CONFIG_RTE_ETHDEV_PROFILE_WITH_VTUNE`` enabled. | |
7c673cae FG |
42 | |
43 | ||
44 | Profiling on ARM64 | |
45 | ------------------ | |
46 | ||
47 | Using Linux perf | |
48 | ~~~~~~~~~~~~~~~~ | |
49 | ||
50 | The ARM64 architecture provide performance counters to monitor events. The | |
51 | Linux ``perf`` tool can be used to profile and benchmark an application. In | |
52 | addition to the standard events, ``perf`` can be used to profile arm64 | |
53 | specific PMU (Performance Monitor Unit) events through raw events (``-e`` | |
54 | ``-rXX``). | |
55 | ||
56 | For more derails refer to the | |
57 | `ARM64 specific PMU events enumeration <http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.100095_0002_04_en/way1382543438508.html>`_. | |
58 | ||
59 | ||
60 | High-resolution cycle counter | |
61 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
62 | ||
63 | The default ``cntvct_el0`` based ``rte_rdtsc()`` provides a portable means to | |
64 | get a wall clock counter in user space. Typically it runs at <= 100MHz. | |
65 | ||
66 | The alternative method to enable ``rte_rdtsc()`` for a high resolution wall | |
9f95a23c | 67 | clock counter is through the ARMv8 PMU subsystem. The PMU cycle counter runs |
7c673cae FG |
68 | at CPU frequency. However, access to the PMU cycle counter from user space is |
69 | not enabled by default in the arm64 linux kernel. It is possible to enable | |
70 | cycle counter for user space access by configuring the PMU from the privileged | |
71 | mode (kernel space). | |
72 | ||
73 | By default the ``rte_rdtsc()`` implementation uses a portable ``cntvct_el0`` | |
74 | scheme. Application can choose the PMU based implementation with | |
75 | ``CONFIG_RTE_ARM_EAL_RDTSC_USE_PMU``. | |
76 | ||
77 | The example below shows the steps to configure the PMU based cycle counter on | |
9f95a23c | 78 | an ARMv8 machine. |
7c673cae FG |
79 | |
80 | .. code-block:: console | |
81 | ||
82 | git clone https://github.com/jerinjacobk/armv8_pmu_cycle_counter_el0 | |
83 | cd armv8_pmu_cycle_counter_el0 | |
84 | make | |
85 | sudo insmod pmu_el0_cycle_counter.ko | |
86 | cd $DPDK_DIR | |
9f95a23c | 87 | make config T=arm64-armv8a-linux-gcc |
7c673cae FG |
88 | echo "CONFIG_RTE_ARM_EAL_RDTSC_USE_PMU=y" >> build/.config |
89 | make | |
90 | ||
91 | .. warning:: | |
92 | ||
93 | The PMU based scheme is useful for high accuracy performance profiling with | |
94 | ``rte_rdtsc()``. However, this method can not be used in conjunction with | |
95 | Linux userspace profiling tools like ``perf`` as this scheme alters the PMU | |
96 | registers state. |