Allocating tasks to machines in computing clusters is described. In an embodiment a set of tasks associated with a job are received at a scheduler. In an embodiment an index can be computed for each combination of tasks and processors and stored in a lookup table. In an example the index may be include an indication of the preference for the task to be processed on a particular processor, an indication of a waiting time for the task to be processed and an indication of how other tasks being processed in the computing cluster may be penalized by assigning a task to a particular processor. In an embodiment tasks are assigned to a processor by accessing the lookup table, selecting a task for processing using the index and scheduling the selected task for allocation to a processor.