Data stream touch instructions are software-directed asynchronous prefetch
instructions that can improve the performance of a system. Ideally, such
instructions are used in perfect synchronization with the actual memory
fetches that are trying to speed up. In practical situations, it is
difficult to predict ahead of time all side effects of these instructions
and memory access latency/throughput during execution of any large
program. Incorrect usage of such instructions can cause degraded
performance of the system. Thus, it is advantageous to measure the
performance of such instructions.