UP/DOWN PREFETCHER

In a processing system comprising a cache, a method includes monitoring demand cache accesses for a thread to maintain a first running count of a number of times demand cache accesses for the thread are directed to cachelines that are adjacent in a first direction to cachelines that are targets of a set of sampled cache accesses for the thread. In response to determining the first running count has exceeded a first threshold, the method further includes enabling a first prefetching mode in which a received demand cache access for the thread triggers a prefetch request for a cacheline adjacent in the first direction to a cacheline targeted by the received demand cache access.