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™ Amplifier 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.

For more complete information about compiler optimizations, see our Optimization Notice.
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