User Guide

Contents

View Comparison Data

Intel® VTune™
Profiler
compares analysis results and displays difference in a separate result tab
<result1>-<result2>
in the following windows:
  • Summary
    window provides top-level difference for the analysis run.
  • Bottom-up
    window displays difference for functions and their callers per metric.
  • Top-down Tree
    window displays difference for functions and their callees per metric.
  • Caller/Callee
    window displays difference for a selected function, their callers and callees per metric.

Comparing Recompiled Binary Files

By default, the
VTune
Profiler
displays compared functions grouped by the
Call Stack
granularity, which is based on function instances. But you may want to switch to the
Source Function Stack
grouping to get more accurate comparison results in the following cases:
  • You slightly changed the source and recompiled the code.
  • You changed compilation options and recompiled the code.
  • You are comparing results compiled and collected for different Intel microarchitectures
For example, your binary with a
my_f
function was modified with adding a new function
my_f1
and new calls of this function. As a result,
my_f
address has changed. If you compare the results before and after the modification using the default
Call Stack
grouping, the
VTune
Profiler
treats the same functions with different addresses as separate instances and does not compare them:
When the data is aggregated by
Source Function Stack
, the
VTune
Profiler
ignores start addresses and compares functions by source file objects:

Bar Data Respresentation

If you chose the
Bar
format to display the performance data in the
Bottom-up
or
Top-down Tree
window, the
VTune
Profiler
calculates the bar size as follows:
Result Data Column
Difference Column
cell_data_value/absolute_max_value_in_result_column
cell_data_value/max(absolute_max_value_in__1st_result_column, absolute_max_value_in_corresponding_2nd_result_column)
Example: Calculation of the Bar Size
The table below provides an example on how the
VTune
Profiler
calculates the bar size in the compare mode based on the absolute max CPU time value and performance data per column:
CPU Time:r001
CPU Time:r002
CPU Time:Difference
Absolute max value (calculated by the
VTune
Profiler
internally but not exposed in the grid)
10s
20s
20s
Performance data
1s
3s
2s
Bar size
1s/max(10s,20s)
3s/max(10s,20s)
2s/max(10s,20s)

Product and Performance Information

1

Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice.

Notice revision #20110804