User Guide

  • 2020
  • 06/18/2020
  • Public Content

Reducing Task Overhead

Task overhead
is the time spent creating a task and getting it assigned to a thread, and also the time spent stopping or pausing the thread when the task is complete.
Task overhead is proportional to the number of times a task is executed. If you have a task that is executed too frequently or where the average time per task instance is too small, modify your task so it encloses a larger amount of computation. Alternatively, consider using the task chunking feature, which is supported by several parallel frameworks. In this case, the parallel framework groups multiple task executions at run-time.
If the Suitability tool recommends that you reduce task overhead, the parallel task is probably too small. Often this is because you have chosen an inner loop in a leaf function as the location of your parallel site, where you instead should have chosen a function farther up the call tree.
There are two ways to reduce task overhead:
  • Restructure your program to reduce the number of tasks you create. For example, restructure your task annotations and/or code to increase the amount of work that occurs during each task's execution.
  • If available for the selected parallel framework, enable the task chunking feature.
You can reduce task overhead by combining multiple task executions into a single task execution. For example, by merging two tasks into one.

Product and Performance Information


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