From: Jerin Jacob <jerin.jacob@caviumnetworks.com>
To: <dev@dpdk.org>
Cc: <thomas.monjalon@6wind.com>, <john.mcnamara@intel.com>,
Jerin Jacob <jerin.jacob@caviumnetworks.com>
Subject: [dpdk-dev] [PATCH v3] doc: arm64: document DPDK application profiling methods
Date: Tue, 8 Nov 2016 09:02:56 +0530 [thread overview]
Message-ID: <1478575976-12006-1-git-send-email-jerin.jacob@caviumnetworks.com> (raw)
In-Reply-To: <1475657009-11139-1-git-send-email-jerin.jacob@caviumnetworks.com>
Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Signed-off-by: John McNamara <john.mcnamara@intel.com>
---
v3:
Fixed formatting issues:
- Remove the introduction heading and put intro text under the main heading(Thomas)
- Fixed RST formatting issues such as enclosing technical terms in backquotes(John)
Thanks, John for providing the updated version
v2:
-Addressed ARM64 specific review comments(Suggested by Thomas)
http://dpdk.org/dev/patchwork/patch/16362/
---
doc/guides/prog_guide/profile_app.rst | 64 ++++++++++++++++++++++++++++++++++-
1 file changed, 63 insertions(+), 1 deletion(-)
diff --git a/doc/guides/prog_guide/profile_app.rst b/doc/guides/prog_guide/profile_app.rst
index 3226187..54b546a 100644
--- a/doc/guides/prog_guide/profile_app.rst
+++ b/doc/guides/prog_guide/profile_app.rst
@@ -31,8 +31,15 @@
Profile Your Application
========================
+The following sections describe methods of profiling DPDK applications on
+different architectures.
+
+
+Profiling on x86
+----------------
+
Intel processors provide performance counters to monitor events.
-Some tools provided by Intel can be used to profile and benchmark an application.
+Some tools provided by Intel, such as VTune, 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.
@@ -50,3 +57,58 @@ The main situations that should be monitored through event counters are:
Refer to the
`Intel Performance Analysis Guide <http://software.intel.com/sites/products/collateral/hpc/vtune/performance_analysis_guide.pdf>`_
for details about application profiling.
+
+
+Profiling on ARM64
+------------------
+
+Using Linux perf
+~~~~~~~~~~~~~~~~
+
+The ARM64 architecture provide performance counters to monitor events. The
+Linux ``perf`` tool can be used to profile and benchmark an application. In
+addition to the standard events, ``perf`` can be used to profile arm64
+specific PMU (Performance Monitor Unit) events through raw events (``-e``
+``-rXX``).
+
+For more derails refer to the
+`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
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+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.
+
+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
+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``.
+
+The example below shows the steps to configure the PMU based cycle counter on
+an armv8 machine.
+
+.. code-block:: console
+
+ git clone https://github.com/jerinjacobk/armv8_pmu_cycle_counter_el0
+ 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
+
+.. warning::
+
+ The PMU based scheme is useful for high accuracy performance profiling with
+ ``rte_rdtsc()``. However, this method can not be used in conjunction with
+ Linux userspace profiling tools like ``perf`` as this scheme alters the PMU
+ registers state.
--
2.5.5
next prev parent reply other threads:[~2016-11-08 3:33 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-04 10:40 [dpdk-dev] [PATCH] " Jerin Jacob
2016-10-04 12:40 ` Thomas Monjalon
2016-10-04 12:45 ` Jan Viktorin
2016-10-05 8:43 ` [dpdk-dev] [PATCH v2] " Jerin Jacob
2016-10-26 20:07 ` Thomas Monjalon
2016-11-03 12:30 ` Mcnamara, John
2016-11-04 14:00 ` Mcnamara, John
2016-11-08 3:32 ` Jerin Jacob [this message]
2016-11-08 5:57 ` [dpdk-dev] [PATCH v3] " Jianbo Liu
2016-11-10 23:41 ` Thomas Monjalon
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