A processing unit includes a plurality of processing elements and one or more caches. A first thread executes a program that includes one or more prefetch instructions to prefetch information into a first cache. Prefetching is selectively enabled when executing the first thread on a first processing element dependent upon whether one or more second threads previously executed the program on the first processing element. The first thread is then dispatched to execute the program on the first processing element. In some cases, a dispatcher receives the first thread four dispatching to the first processing element. The dispatcher modifies the prefetch instruction to disable prefetching into the first cache in response to the one or more second threads having previously executed the program on the first processing element.