Temperature-aware scheduling: When is systemthrottling good enough

Power-aware operating systems ensure that the system temperature does not exceed a threshold by utilizing system-throttling. In this technique, the system load (or alternatively, the clock speed) is scaled when the temperature hits this threshold. At other times, the system operates at maximum load. In this paper, we show that such simple system-throttling rules are in fact the best one can achieve under certain assumptions. We show that maintaining a constant operating speed (and thus temperature) always does more work than operating in alternating periods of cooling and heating. As a result, for certain settings and for a reasonable temperature model, we prove that system-throttling is the most e®ective temperature aware-scheduling. Naturally, these assumptions do not always hold; we also discuss the scenario when some of our assumptions are relaxed, and argue why one needs more complex scheduling algorithms in this case.