A data processing apparatus includes a processor and a hierarchical data storage system, including a memory and a cache, for storing the data and the instructions in storage locations identified by physical addresses. The apparatus includes address translation circuitry for mapping the virtual addresses to the physical addresses and load store circuitry receiving access requests from the processor. The store circuitry accesses the translation circuitry to identify physical addresses that correspond to virtual addresses of the received data access requests, and to access the corresponding physical addresses in the hierarchical data storage system. Preload circuitry receives preload requests from the processor indicating virtual addresses storage locations that are to be preloaded. Prefetch circuitry monitors at least some of the accesses performed by the load store circuitry and predicts addresses to be accessed subsequently, and transmits the predicted addresses to the preload circuitry as preload requests.