User Guide

  • 2020
  • 06/18/2020
  • Public Content
Contents

Problem: CPU time for Hotspots or Threading Analysis is Too Low

Cause

The CPU time is low for one of the following reasons:
  • The analysis run was very short and the target consumed little CPU time.
  • CPU time may be inaccurate for targets that work in short quanta less than the scheduler tick interval. For example, this can happen for frame-by-frame computation in video decoders. To capture CPU time more accurately on Windows* OS, you need to run the analysis with the accurate CPU time detection mode enabled.

Solution

Try one of the following:
  • Extend the duration of the analysis run.
  • Windows OS only: Enable accurate CPU time detection. To do this for the Hotspots or Threading analysis, it is enough to run the
    VTune
    Profiler
    with administrative permissions. You may also enable this option explicitly in the custom analysis configuration by checking the
    Collect highly accurate CPU time
    box. Make sure to extend maximum size of raw collector data.
Accurate CPU time collection produces a significant amount of temporary data depending on the system configuration and the profiled target.
VTune
Profiler
may generate up to 5 Mb of temporary data per minute per logical CPU.

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