1. A processor comprising: a plurality of processor cores, each of which is arranged to perform processing tasks, and wherein at least one of the processor cores is of a different architecture than the other core(s); a scheduler that is arranged to receive task identifiers of respective processing tasks from a task queue and to allocate a selected core of the processor cores for each respective processing task received from the task queue; and a hint generator that is arranged to monitor performance constraint parameters of the processor during operation of the processor and to generate a hint in response to the monitored performance parameters, wherein the scheduler is arranged to allocate the respective processing task from the task queue to the selected core in response to the generated hint, wherein the generated hint is generated in response to a bias threshold determined in response to a first comparison of a first monitored performance constraint parameter with a first system constraint setting and to a second comparison of a second monitored performance constraint parameter with a second system constraint setting, wherein the selected core is arranged to execute the respective processing task from the task queue, wherein the hint generator is arranged to store the first and the second system constraint settings, and wherein the bias threshold is determined using a weighting factor for each of the first and second system constraint settings.