Potential Gain shows the maximum time that could be saved if the OpenMP region is optimized to have no load imbalance assuming no runtime overhead (Parallel Region Time minus Region Ideal Time). If the Potential Gain is large, make sure the workload for this region is enough and the loop schedule is optimal.
VTuneuses the following methodology to calculate the Potential Gain metric that is a sum of inefficiencies normalized by the number of threads:
The time wasted on load imbalance or parallel work arrangement is significant and negatively impacts the application performance and scalability. Explore OpenMP regions with the highest metric values. Make sure the workload of the regions is enough and the loop schedule is optimal.