Intel® VTune™ Profiler User Guide

User Guide

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.
    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:

Product and Performance Information

1

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