Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Mon, 10 Sep 2018 22:17:55 +0200 | Subject | Re: [PATCH v2] cpuidle: enter_state: Don't needlessly calculate diff time |
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On Mon, Sep 10, 2018 at 7:40 PM Fieah Lim <kw@fieahl.im> wrote: > > Currently we use ktime_us_delta() to calculate last residency and > state usage unconditionally, it makes no sense to do this calculation > when we fails to enter any idle state. > It can be optimize by moving the calculation after entered_state >= 0 > > While at it, merge those comment blocks into one and remove a > space between type casting of diff. > > This patch has no functional changes. > > Signed-off-by: Fieah Lim <kw@fieahl.im> > --- > Changes from v1: > - Rewrite changelog as Rafael J. Wysocki suggested > --- > drivers/cpuidle/cpuidle.c | 17 ++++++++--------- > 1 file changed, 8 insertions(+), 9 deletions(-) > > diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c > index 6df894d65d9e..5f6b2c9b6555 100644 > --- a/drivers/cpuidle/cpuidle.c > +++ b/drivers/cpuidle/cpuidle.c > @@ -247,21 +247,20 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv, > if (!cpuidle_state_is_coupled(drv, index)) > local_irq_enable(); > > - diff = ktime_us_delta(time_end, time_start); > - if (diff > INT_MAX) > - diff = INT_MAX; > - > - dev->last_residency = (int) diff; > + dev->last_residency = 0;
You don't need this line if you retain the "else" branch below, do you?
> > if (entered_state >= 0) { > - /* Update cpuidle counters */ > - /* This can be moved to within driver enter routine > + /* Update cpuidle counters > + * This can be moved to within driver enter routine, > * but that results in multiple copies of same code. > */ > + diff = ktime_us_delta(time_end, time_start); > + if (diff > INT_MAX) > + diff = INT_MAX; > + > + dev->last_residency = (int)diff; > dev->states_usage[entered_state].time += dev->last_residency; > dev->states_usage[entered_state].usage++; > - } else { > - dev->last_residency = 0; > } > > return entered_state; > -- > 2.18.0 >
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