User Guide

Intel® VTune™ Profiler User Guide

ID 766319
Date 12/16/2022
Public

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Document Table of Contents

Analyze Loops

Use the Intel® VTune™ Profiler to view a hierarchy of the loops in your application call tree and identify code sections for optimization.

To view and analyze loops in your application:

  1. Create a custom analysis (for example, Loop Analysis) based on hardware event-based collection and select the Analyze loops, Estimate call counts, and Estimate trip counts options.
  2. Select the required filtering level from the Loop Mode drop-down menu on the Filter toolbar.
    • Loops only: Display loops as regular nodes in the tree. Loop name consists of:

      • start address of the loop

      • number of the code line where this loop is created

      • name of the function where this loop is created

    • Loops and functions: Display both loops and functions as separate nodes.

    • Functions only (default): Display data by function with no loop information.

    VTune Profiler updates the grid according to the selected filtering level.

  3. Analyze Self and Total metrics in the Bottom-up and Top-down Tree windows and identify the most time-consuming loops.
  4. Double-click a loop of interest to view the source code.

    VTune Profiler opens a source file for the function with the selected loop. The code line creating the loop is highlighted.

    NOTE:

    You can see the code line information only if debug information for your function is available.

Examples

To identify the most time-consuming loop, select the Loops only mode in the Bottom-up window. By default, loops with the highest CPU Time values show up at the top of the grid.

To identify the heaviest top-level loops, switch to the Top-down Tree window. The data in the grid is sorted by the Total time metric displaying the hottest top-level loops first: