Intel VTune Amplifier

Introduction

Intel VTune Amplifier, part of Intel Parallel studio, is a GUI profiling tool designed for Intel processors. It offers a graphical performance analysis of single core and multithreaded applications. A highlight of the features:

  • Hotspot analysis
  • Locks and waits analysis
  • Low level specific counters, such as branch analysis and memory bandwidth
  • Power usage analysis - frequency and sleep states.

screenshot

Usage

To launch the GUI, first load the module:

$ module add VTune/2016_update1

and launch the GUI :

$ amplxe-gui

Note

To profile an application with VTune Amplifier, special kernel modules need to be loaded. The modules are not loaded on Anselm login nodes, thus direct profiling on login nodes is not possible. Use VTune on compute nodes and refer to the documentation on using GUI applications.

The GUI will open in new window. Click on "New Project..." to create a new project. After clicking OK, a new window with project properties will appear. At "Application:", select the bath to your binary you want to profile (the binary should be compiled with -g flag). Some additional options such as command line arguments can be selected. At "Managed code profiling mode:" select "Native" (unless you want to profile managed mode .NET/Mono applications). After clicking OK, your project is created.

To run a new analysis, click "New analysis...". You will see a list of possible analysis. Some of them will not be possible on the current CPU (e.g. Intel Atom analysis is not possible on Sandy Bridge CPU), the GUI will show an error box if you select the wrong analysis. For example, select "Advanced Hotspots". Clicking on _Start _will start profiling of the application.

Remote Analysis

VTune Amplifier also allows a form of remote analysis. In this mode, data for analysis is collected from the command line without GUI, and the results are then loaded to GUI on another machine. This allows profiling without interactive graphical jobs. To perform a remote analysis, launch a GUI somewhere, open the new analysis window and then click the button "Command line" in bottom right corner. It will show the command line needed to perform the selected analysis.

The command line will look like this:

$ /apps/all/VTune/2016_update1/vtune_amplifier_xe_2016.1.1.434111/bin64/amplxe-cl -collect advanced-hotspots -knob collection-detail=stack-and-callcount -mrte-mode=native -target-duration-type=veryshort -app-working-dir /home/sta545/test -- /home/sta545/test_pgsesv

Copy the line to clipboard and then you can paste it in your jobscript or in command line. After the collection is run, open the GUI once again, click the menu button in the upper right corner, and select "Open > Result...". The GUI will load the results from the run.

Xeon Phi

Note

This section is outdated. It will be updated with new information soon.

It is possible to analyze both native and offload Xeon Phi applications. For offload mode, just specify the path to the binary. For native mode, you need to specify in project properties:

Application: ssh

Application parameters: mic0 source ~/.profile && /path/to/your/bin

Note that we include source ~/.profile in the command to setup environment paths as described here.

Note

If the analysis is interrupted or aborted, further analysis on the card might be impossible and you will get errors like "ERROR connecting to MIC card". In this case please contact our support to reboot the MIC card.

You may also use remote analysis to collect data from the MIC and then analyze it in the GUI later :

$ amplxe-cl -collect knc-hotspots -no-auto-finalize -- ssh mic0
    "export LD_LIBRARY_PATH=/apps/intel/composer_xe_2015.2.164/compiler/lib/mic/:/apps/intel/composer_xe_2015.2.164/mkl/lib/mic/; export KMP_AFFINITY=compact; /tmp/app.mic"

References

  1. https://www.rcac.purdue.edu/tutorials/phi/PerformanceTuningXeonPhi-Tullos.pdf Performance Tuning for Intel® Xeon Phi™ Coprocessors