A method of data processing in a processing unit supported by a memory hierarchy includes the processing unit performing a plurality of memory accesses to the memory hierarchy. The plurality of memory accesses includes one or more memory accesses targeting a full cache line of data. The processing unit monitors utilization of data accessed by the plurality of memory accesses, and based upon the utilization of the data, dynamically alters a memory access mode of operation so that a subsequent storage-modifying memory access targets less than a full cache line of data.