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Intel VTune Profiler

Introduction

Intel® VTune™ Profiler, 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.

Usage

To profile an application with VTune Profiler, special kernel modules need to be loaded. The modules are not loaded on the login nodes, thus direct profiling on login nodes is not possible. By default, the kernel modules are not loaded on compute nodes either. In order to have the modules loaded, you need to specify the vtune=version PBS resource at job submit. The version is the same as for the environment module. For example, to use VTune/2020_update2-GCC:

$ qsub -q qexp -A OPEN-0-0 -I -l select=1,vtune=2020_update2-GCC

After that, you can verify that the modules sep*, pax, and vtsspp are present in the kernel:

login@cn191:~$ lsmod | grep -e sep -e pax -e vtsspp
vtsspp                367418  0
sep5                  885333  0
socperf3              595104  2 sep5,socwatch2_12
pax                    13820  0

To launch the GUI, first load the module:

$ ml VTune/2020_update2-GCC

and launch the GUI:

$ vtune-gui

Warning

The command line amplxe-gui is deprecated. Use vtune-gui instead.

The GUI will open in a 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 path to your binary you want to profile (the binary should be compiled with the -g flag). You can also select some additional options such as command line arguments. Click OK to create the project.

To run a new analysis, click "New analysis...". You will see a list of possible analyses. Some of them will not be possible on the current CPU, the GUI will show an error box if you select a wrong analysis. Clicking on Start will start profiling of the application.

Remote Analysis

VTune Profiler 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 "Command line" button in the 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/2020_update2-GCC/vtune_profiler_2020.2.0.610396/bin64/vtune -collect hotspots -app-working-dir /home/$USER/tmp -- /home/$USER/tmp/sgemm

Warning

The command line amplxe-cl is a relative link to command vtune.

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

References

  1. Intel® VTune™ Amplifier Support
  2. Amplifier Help Linux

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