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    SubjectRe: [RFC PATCH v1 00/11] Create fast idle path for short idle periods
    On Fri, Jul 14, 2017 at 09:03:14AM -0700, Andi Kleen wrote:
    > fast idle doesn't have an upper bound.
    >
    > If the prediction exceeds the fast idle threshold any C state can be used.
    >
    > It's just another state (fast C1), but right now it has an own threshold
    > which may be different from standard C1.

    Given it uses the same estimate we end up with:

    select_c_state(idle_est)
    {
    if (idle_est < fast_threshold)
    return C1;

    if (idle_est < C1_threshold)
    return C1;
    if (idle_est < C2_threshold)
    return C2;
    /* ... */

    return C6
    }

    Now, unless you're mister Turnbull, C2 will never get selected when
    fast_threshold > C2_threshold.

    Which is wrong. If you want to effectively scale the selection of C1,
    why not also change the C2 and further criteria.

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