Intel® VTune™ Amplifier
To streamline memory operations in the pipeline, a load can avoid waiting for memory if a prior store, still in flight, is writing the data that the load wants to read (a 'store forwarding' process). However, in some cases, when the prior store is writing a smaller region than the load is reading, the load is blocked for a significant time pending the store forward. This metric measures the fraction of demand loads that were blocked by store forwarding.
Loads are blocked during store forwarding for a significant proportion of loads. Use source/assembly view to identify the blocked loads, then identify the problematically-forwarded stores, which will typically be within the ten dynamic instructions prior to the load. If the forwarding store is smaller than the load, change the store to be the same size as the load.