Apparatus and computing systems associated with cache sharing based thread control are described. One embodiment includes a memory to store a thread control instruction and a processor to execute the thread control instruction. The processor is coupled to the memory. The processor includes a first unit to dynamically determine a cache sharing behavior between threads in a multi-threaded computing system and a second unit to dynamically control the composition of a set of threads in the multi-threaded computing system. The composition of the set of threads is based, at least in part, on thread affinity as exhibited by cache-sharing behavior. The thread control instruction controls the operation of the first unit and the second unit.