Pulling heavy tasks and pushing light tasks across multiple processor units of differing capacity

Abstract

A mechanism is provided for scheduling tasks across multiple processor units of differing capacity. In a multiple processor unit system with processor units of disparate speeds, it is advantageous to have the most processing-intensive tasks run on the processor units with the highest capacity. All tasks are initially scheduled on the lowest capacity processor units. Because processor units with higher capacity are more likely to have idle time, these higher capacity processor units may pull one or more tasks onto themselves from the same or lower capacity processor units. A processor unit will attempt to pull tasks that utilize a larger percentage of the timeslice. When a higher capacity processor unit is overloaded or near capacity, the higher capacity processor unit may push tasks to processor units with the same or lower capacity. A processor unit will attempt to push tasks that utilize a smaller percentage of the timeslice.