Imbalance or Serial Spinning

Metric Description

Imbalance or Serial Spin time is wall time when working threads are spinning on a synchronization barrier consuming CPU resources. High metric value on parallel regions can be caused by load imbalance or inefficient concurrency of all working threads. To address load imbalance, consider applying dynamic work scheduling. High metric value on serial execution (Serial - outside any region) can indicate that serial application time is significant and limiting efficient processor utilization. Explore options for parallelization, algorithm or microarchitecture tuning of the serial part of the application.

Possible Issues

CPU time spent waiting on an OpenMP barrier inside of a parallel region can be a result of load imbalance. Where relevant, try dynamic work scheduling to reduce the imbalance. High metric value on serial execution (Serial - outside any region) may signal significant serial application time that is limiting efficient processor utilization. Explore options for parallelization, algorithm or microarchitecture tuning of the serial part of the application.

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