.. _acrntrace:
Acrntrace
#########
Description
***********
``acrntrace`` is a tool running on the Service OS (SOS) to capture trace data.
A ``scripts`` directory includes scripts to analyze the trace data.
Usage
*****
Acrntrace
=========
The ``acrntrace`` tool runs on the Service OS (SOS) to capture trace data and
output to trace file under ``./acrntrace`` with raw (binary) data format.
Options:
-h print this message
-i period specify polling interval in milliseconds [1-999]
-t max_time max time to capture trace data (in second)
-c clear the buffered old data (deprecated)
-r capture the buffered old data instead of clearing it
-a cpu-set only capture the trace data on the configured cpu-set
acrntrace_format.py
===================
The ``acrntrace_format.py`` is an offline tool for parsing trace data (as output
by acrntrace) to human-readable formats based on a given format.
Here's an explanation of the tool's parameters:
.. code-block:: none
acrntrace_format.py [options] [formats] [trace_data]
Options:
-h print this message
The *formats* file specifies the rules to reformat the *trace_data* collected by
``acrntrace`` into a human-readable text form. The rules in this file follow
this form::
event_id text_format_string
The ``text_format_string`` may include format specifiers, such as
``%(cpu)d``, ``%(tsc)d``, ``%(event)d``, ``%(1)d``, and ``%(2)d``.
The 'd' format specifier outputs decimals. Alternatively 'x' will
output in hexadecimals and 'o' will output in octals.
These respectively correspond to the CPU number (cpu), timestamp
counter (tsc), event ID (event), and the data logged in the trace file.
There can be only one such rule for each type of event.
An example *formats_file* is available in the acrn_hypervisor repo in
``hypervisor/tools/acrntrace/scripts/formats``.
acrnalyze.py
============
The ``acrnalyze.py`` is a offline tool to analyze trace data (as output by
acrntrace) based on a given analyzer, such as ``vm_exit`` or ``irq``.
Options:
.. list-table::
* - :kbd:`-h`
- print this message
* - :kbd:`-i, --ifile=string`
- input file name
* - :kbd:`-o, --ofile=string`
- output file name
* - :kbd:`-f, --frequency=unsigned_int`
- TSC frequency in MHz
* - :kbd:`--vm_exit`
- generate a vm_exit report
* - :kbd:`--irq`
- generate an IRQ-related report
.. note:: We depend on TSC frequency to do time-based analysis. Be sure to configure
the right TSC frequency that acrn runs on. TSC frequency can be obtained
from the ACRN console log (calibrate_tsc, tsc_hz=xxx) when the hypervisor boots.
The tool does not take into account CPU frequency variation that can
occur during normal operation (aka CPU throttling) on the processor which
doesn't support for an invariant TSC. The results may therefore not be
completely accurate in that regard.
Typical Use Example
===================
Here's a typical use of ``acrntrace`` to capture trace data from the SOS,
convert the binary data to human-readable form, copy the processed trace
data to your Linux system, and run the analysis tool.
1. On the SOS, clear buffers before starting a trace using:
.. code-block:: none
# acrntrace -c
#. Start capturing buffered trace data using:
.. code-block:: none
# acrntrace
Trace files are created under the current directory where we launch acrntrace,
with a date-time-based directory name such as ``./acrntrace/20171115-101605``
#. When done, stop a running ``acrntrace`` using:
.. code-block:: none
q <enter>
#. Convert trace data to human-readable format using:
.. code-block:: none
# acrntrace_format.py formats trace_data
Trace data will be converted to human-readable format based on a given format
and printed to stdout.
#. Analysis of the collected data is done on a Linux PC so you'll need
to copy the collected trace data to your Linux system (using ``scp`` is
recommended):
.. code-block:: none
# scp -r ./acrntrace/20171115-101605/ \
username@hostname:/home/username/trace_data
Replace username and hostname with appropriate values.
#. On the Linux system, run the provided Python3 script to analyze the
``vm_exits``, ``irq``:
.. code-block:: none
# acrnalyze.py -i /home/xxxx/trace_data/20171115-101605/0 \
-o /home/xxxx/trace_data/20171115-101605/cpu0 --vm_exit --irq
- The analysis report is written to stdout, or to a CSV file if
a file name is specified using ``-o filename``.
- The scripts require Python3.
Build and Install
*****************
The source files for ``acrntrace`` are in the ``tools/acrntrace`` folder,
and can be built and installed using:
.. code-block:: none
# make
# make install
The processing scripts are in ``tools/acrntrace/scripts`` and need to be
copied to and run on your Linux system.
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