Developer Guide

Contents

Tracing Applications

The Intel® MPI Library provides a variety of options for analyzing MPI applications. Some of these options are available within the Intel MPI Library, while some require additional analysis tools. For these tools, the Intel MPI Library provides compilation and runtime options and environment variables for easier interoperability.
The Intel MPI Library is tightly integrated with the Intel® Trace Analyzer and Collector, which enables you to analyze and debug MPI applications. The Intel MPI Library has several compile-
and run
time options to simplify the application analysis.
Apart from the Intel Trace Analyzer and Collector, there is also a tool called Application Performance Snapshot intended for a higher level MPI analysis.
Intel Trace Analyzer and Collector is available as standalone software and as part of the Intel® oneAPI HPC Toolkit. Before proceeding to the next steps, make sure you have the product installed.

High-Level Performance Analysis

For a high-level application analysis, Intel provides a lightweight analysis tool Application Performance Snapshot (APS), which can analyze MPI and non-MPI applications. The tool provides general information about the application, such as MPI and OpenMP* utilization time and load balance, MPI operations usage, memory and disk usage, and other information. This information enables you to get a general idea about the application performance and identify spots for a more thorough analysis.
Follow these steps to analyze an application with the APS:
  1. Set up the environment for the compiler, Intel MPI Library, and APS.
    $ source <install-dir>/setvars.sh
    $ source<install-dir>/vtune/<version>/env/vars.sh
  2. Run your application with the
    -aps
    option of
    mpirun
    :
    $ mpirun -n 4 -aps ./myprog
    APS will generate a directory with the statistics files
    aps_result_<
    date
    >-<
    time
    >
    .
  3. Launch the
    aps-report
    tool and pass the generated statistics to the tool:
    $ aps-report ./aps_result_<date>-<time>
    You will see the analysis results printed in the console window. Also, APS will generate an HTML report
    aps
    _report_<
    date
    >_<
    time
    >.html
    containing the same information.
For more details, refer to the
Application Performance Snapshot User Guide
.

Trace an Application

To analyze an application
with the Intel Trace Analyzer and Collector
, first you need generate a trace file of your application, and then open this file in Intel® Trace Analyzer to analyze communication patterns, time utilization, etc. Tracing is performed by
preloading
the Intel Trace Collector profiling library
at runtime
, which intercepts all MPI calls and generates a trace file. Intel MPI Library provides the
-trace
(
-t
) option to simplify this process.
Complete the following steps:
  1. Set up the environment for the Intel MPI Library, and Intel Trace Analyzer and Collector.
    $ source <mpi-install-dir>/env/vars.sh
    $ source <itac-install-dir>/env/vars.sh
  2. Trace
    your application with the Intel Trace Collector:
    $ mpirun -trace -n 4 ./myprog
    As a result, a trace file
    .stf
    is generated. For the example above, it is
    myprog.stf
    .
  3. Analyze the application with the Intel Trace Analyzer:
    $ traceanalyzer ./myprog.stf &
The workflow above is the most common scenario of tracing with the Intel Trace Collector. For other tracing scenarios, see the Intel Trace Collector documentation.

Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.