Intel® VTune™ Profiler User Guide

User Guide

Contents

MPI Busy Wait Time

Metric Description

MPI Busy Wait Time is CPU time when MPI runtime library is spinning on waits in communication operations. High metric value can be caused by load imbalance between ranks, active communications or nonoptimal settings of MPI library. Explore details on communication inefficiencies with Intel® Trace Analyzer and Collector.

Possible Issues

CPU time spent on waits for MPI communication operations is significant and can negatively impact the application performance and scalability. This can be caused by load imbalance between ranks, active communications or non-optimal settings of MPI library. Explore details on communication inefficiencies with Intel Trace Analyzer and Collector.

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