COOLIP: Simple yet effective job allocation for distributed thermally-throttled processors

Thermal constraints limit the time for which a processor can run at high frequency. Such thermal-throttling complicates the computation of response times of jobs. For multiple processors, a key decision is where to allocate the next job. For distributed thermally-throttled procesosrs, we present COOLIP with a simple allocation policy: a job is allocated to the earliest available processor, and if there are several available simultaneously, to the coolest one. For Poisson distribution of inter-arrival times and Gaussian distribution of execution demand of jobs, COOLIP matches the 95-percentile response time of Earliest Finish-Time (EFT) policy which minimizes response time with full knowledge of execution demand of unfinished jobs and thermal models of processors. We argue that COOLIP performs well because it directs the processors into states such that a defined sufficient condition of optimality holds.