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    SubjectRe: [PATCH] cpuidle: menu: use nr_running instead of cpuload for calculating perf mult
    On Mon, 2012-06-04 at 08:39 -0700, Arjan van de Ven wrote:

    > hmm I think you're missing the whole point.

    Probably.. as I've still no clue what you're wanting to do.

    > > I'm just not buying load actually matters or works, if there's lots of
    > > idle time load history should be low, if there's not a lot of idle time,
    > > you're busy (per definition) and again load isn't important.
    > if there is a lot of idle, load can be low or high; load is more than
    > just cpu usage. it includes waiting for resources and mutexes etc.

    It very much does not. The thing its using: this_cpu_load() returns
    rq->cpu_load[0], does not include blocked tasks of any kind.

    > if load is low, you are idle, sure (in that direction it works). If load
    > is low, the heuristic that is used here will not hinder a deep C state
    > choice.
    > if there is not a lot of idle time, sure, load is high.

    False, you can have 0 idle time and still have low load.

    > but because idle
    > time tends to be bursty, we can still be idle for, say, a millisecond
    > every 10 milliseconds. In this scenario, the load average is used to
    > ensure that the 200 usecond cost of exiting idle is acceptable.

    So what you're saying is that if you have 1ms idle in 10ms, it might not
    be a continuous 1ms. And you're using load as a measure of how many
    fragments it comes apart in?

    That's not making sense.

    > one other way of doing this would be tracking cumulative accrued latency
    > as a percentage of cpu busy time... but that's also a pretty
    > approximative measure.

    To what purpose? I'm completely confused now, none of what you say is
    making any sense.

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      Last update: 2012-06-04 19:21    [W:0.023 / U:6.840 seconds]
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