User Guide

  • 2020
  • 06/18/2020
  • Public Content

MUX Reliability

Metric Description

This metric estimates reliability of HW event-related metrics. Since the number of collected HW events exceeds the number of counters,
Intel® VTune™
uses event multiplexing (MUX) to share HW counters and collect different subsets of events over time. This may affect the precision of collected event data. The ideal value for this metric is 1. If the value is less than 0.7, the collected data may be not reliable.

Possible Issues

Precision of collected HW event data is not enough. Metrics data may be unreliable. Consider increasing your application execution time, using the multiple runs mode instead of event multiplexing, or creating a custom analysis with a limited subset of HW events. If you are using a driverless collection, consider reducing the value of /sys/bys/event_source/devices/cpu/perf_event_mux_interval_ms file.
A high value for this metric does not guarantee an accuracy of the hardware-based metrics. However, a low value definitely puts the metrics in question and you should re-run the analysis using the
Allow multiple runs
option or increase the execution time to improve the accuracy.

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