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Rethinking power-aware scheduling

Rethinking power-aware scheduling

Posted Jan 14, 2012 22:48 UTC (Sat) by dlang (subscriber, #313)
In reply to: Rethinking power-aware scheduling by raven667
Parent article: Rethinking power-aware scheduling

there is no way to have power savings with no performance penalty under any conditions.

it takes time to bring CPUs out of sleep states, and during that time the work that is waiting for them may not be able to get done.

it is not always less power to run at full speed and then sleep, that is frequently the case, but it depends on the ability to move in and out of sleep, along with the amount of power saved.

In this case, we are talking about the options when you have multiple cores, some sharing components, and have less work than it takes to max out all the cores.

putting all the work on one core and powering off the other cores may save power, but it could make the work take longer (but not enough longer to use more power than the other cores would consume if they were not powered down). for some people having the work take slightly longer won't matter, for others it will.

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Rethinking power-aware scheduling

Posted Jan 15, 2012 3:53 UTC (Sun) by raven667 (subscriber, #5198) [Link]

There is no reason to think that a power aware scheduler can't be good enough to be the default, is there? Even for latency sensitive operations the scheduler could keep some amount of idle capacity available for bursts of work without running the whole machine at full bore. It seems to me that power saving should be the default even for machines on mains power

Rethinking power-aware scheduling

Posted Jan 15, 2012 13:48 UTC (Sun) by mjg59 (subscriber, #23239) [Link]

Nonsense. Turbo mode is an example of aggressive power management resulting in significantly enhanced performance under certain workloads.

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