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    SubjectRe: [RESEND PATCH v2 1/2] power/cpuidle: enhance the precision of state select
    On Fri, Jun 17, 2016 at 11:13 AM, Zhaoyang Huang
    <zhaoyang.huang@linaro.org> wrote:
    > In previous version, cpu_pm_enter is invoked

    By whom? Not by the core surely?

    > after the governor select the state, which cause the executing time of cpu_pm_enter
    > is included in the idle time. Moving it before the state selection.
    >
    > Signed-off-by: Zhaoyang Huang <zhaoyang.huang@spreadtrum.com>
    > ---
    > kernel/sched/idle.c | 18 ++++++++++++------
    > 1 file changed, 12 insertions(+), 6 deletions(-)
    >
    > diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
    > index bd12c6c..929da2e 100644
    > --- a/kernel/sched/idle.c
    > +++ b/kernel/sched/idle.c
    > @@ -5,6 +5,7 @@
    > #include <linux/cpu.h>
    > #include <linux/cpuidle.h>
    > #include <linux/cpuhotplug.h>
    > +#include <linux/cpu_pm.h>
    > #include <linux/tick.h>
    > #include <linux/mm.h>
    > #include <linux/stackprotector.h>
    > @@ -130,6 +131,7 @@ static void cpuidle_idle_call(void)
    > struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
    > struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
    > int next_state, entered_state;
    > + int ret;
    >
    > /*
    > * Check if the idle task must be rescheduled. If it is the
    > @@ -174,12 +176,16 @@ static void cpuidle_idle_call(void)
    > /*
    > * Ask the cpuidle framework to choose a convenient idle state.
    > */
    > - next_state = cpuidle_select(drv, dev);
    > - entered_state = call_cpuidle(drv, dev, next_state);
    > - /*
    > - * Give the governor an opportunity to reflect on the outcome
    > - */
    > - cpuidle_reflect(dev, entered_state);
    > + ret = cpu_pm_enter();

    "To move" usually means "take it away from there and put it here" as
    far as kernel patches are concerned, but I only see it added here.

    > + if (!ret) {
    > + next_state = cpuidle_select(drv, dev);
    > + entered_state = call_cpuidle(drv, dev, next_state);
    > + cpu_pm_exit();
    > + /*
    > + * Give the governor an opportunity to reflect on the outcome
    > + */
    > + cpuidle_reflect(dev, entered_state);
    > + }
    > }
    >
    > exit_idle:
    > --

    No way I will agree to add that notification stuff to the core.

    Thanks,
    Rafael

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