VTune

VTune is a software performance analysis tool provided by Intel for users developing serial, multithreaded or MPI applications.

Documentation:

 

Usage

 

To use VTune:

  • Connect to Bridges using an ssh client with X11 forwarding enabled
  • Run VTune in an interactive session on Bridges that profiles your code
  • Examine the output from VTune

 Follow these steps:

  1. Connect to Bridges with X11 forwarding enabled

    Connect to Bridges using ssh with X11 forwarding enabled.  This is important - otherwise, you will not be able to use the GUI supplied with VTune to examine the output.

  2. Run an interactive session that profiles your code.
    1. Start an interactive session with the interact command.
      interact -n X

      where X is the number of cores that you want to use. This will request resources in the RM-shared partition for 60 minutes. You can override these defaults by using other options to the interact command.

      See more about running interactive sessions on Bridges.

    2. Compile your code as usual, if necessary.
    3. Load the vtune module
      module load vtune

      Now amplxe-gui (the GUI) and ample-cl (the command-line interface) are defined for you.

    4. Profile your code by running ample-cl and passing your code to it.

      For a non-MPI code, the command will look like:

      amplxe-cl -result-dir dirname -quiet -collect hotspots ./your-executable arguments-to-your-executable

      If you are profiling an MPI code, use mpirun to execute amplxe-cl

      mpirun -np X amplxe-cl -result-dir dirname -quiet -collect hotspots ./your-executable arguments-to-your-executable

       

      In either case, dirname is any name you choose. The data from VTune will be stored in a new directory(s) named dirname.$hostname, where $hostname is the fully qualified name for the nodes allocated to your interactive session.  VTune will create a directory for each node you are using.  $hostname will be of the form 'rxxx.pvt.bridges.psc.edu'.

      The profiling data will be stored in a file with the same name as the directory and the extension 'amplxe'.

    5. Once amplxe-cl completes, exit your interactive session with Ctrl-D.

     

  3. Examine the profiling information
    1. Move to the new directory created by amplxe-cl
      cd dirname.$hostname
    2. Load the VTune module
      module load vtune
    3. Start the GUI and open the .amplxe file.
      amplxe-gui dirname.$hostname.amplxe

      The GUI has many options.  Information on using it is available at https://software.intel.com/en-us/node/543997

More information

The tutorials referenced above will take you step-by-step through analyzing code performance. Sample codes are included.

 

 

 

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Send mail to remarks@psc.edu or call the PSC hotline: 412-268-6350.