schedulingforreducedcpuenergy(文件)
【正文】 s s o ra re n e e d e d t o s e e t h i s p i c t u r e . Lower min. voltage = more excess cycles Longer intervals = accumulate more excess cycles Energy savings is function of the interval size Evaluation: Average Excess Cycles [2] Q u i c k T i m e ? a n d a d e c o m p r e s s o ra re n e e d e d t o s e e t h i s p i c t u r e . Discussion amp。 undesirable ? Bad response time ? FUTURE (boundeddelay limitedfuture) ? Taking the future trace of a small window ? Window sizes: 1 ms ~ 400 sec ? Impractical but desirable ? Good response time on a window of 10 to 50 ms Scheduling Algorithms cont’d ? PAST (boundeddelay limitedpast) ? Looking a fixed window into the past ? Assuming the next window will be like the previous one ? Examine % busy during the pervious interval and adjust speed for the next interval ? Excess cycles can build up if speed (+voltage) is set too low. = Penalty metric ? Excess Cycle Penalty ? At each interval, count up left over cycles that accumulated because you ran too slow ? Switch to full speed if there were more excess cycles than idle time in the previous interval ? Hard idle (page fault, disk request) cannot be squeezed Trace Driven Simulation ? Trace Points ? Sched: context switch away a process ? Idle on: enter the idle loop ? Idle off: leave idle loop to
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