linux-kernel - Re: [RFC v3 1/3] PM/runtime: Add a new interface to get accounted time

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Date:   Wed, 19 Dec 2018 16:25:08 +0100
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Thara Gopinath <thara.gopinath@...aro.org>,
        jani.nikula@...ux.intel.com,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        rodrigo.vivi@...el.com, David Airlie <airlied@...ux.ie>,
        "Intel graphics driver community testing & development" 
        <intel-gfx@...ts.freedesktop.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>
Subject: Re: [RFC v3 1/3] PM/runtime: Add a new interface to get accounted time

On Wed, 19 Dec 2018 at 10:58, Ulf Hansson <ulf.hansson@...aro.org> wrote:
>
> On Tue, 18 Dec 2018 at 15:55, Vincent Guittot
> <vincent.guittot@...aro.org> wrote:
> >
> > Some drivers (like i915/drm) need to get the accounted suspended time.
> > pm_runtime_accounted_time_get() will return the suspended or active
> > accounted time until now.
>
> I suggest to leave the active accounted time out for now. At least
> until we have some users.
>
> That said, perhaps rename the function to something along the lines
> of, pm_runtime_last_suspended_time(), to make it more clear.
>
> >
> > Signed-off-by: Vincent Guittot <vincent.guittot@...aro.org>
> > ---
> >  drivers/base/power/runtime.c | 26 ++++++++++++++++++++++++++
> >  include/linux/pm_runtime.h   |  2 ++
> >  2 files changed, 28 insertions(+)
> >
> > diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
> > index 7062469..6461469 100644
> > --- a/drivers/base/power/runtime.c
> > +++ b/drivers/base/power/runtime.c
> > @@ -88,6 +88,32 @@ static void __update_runtime_status(struct device *dev, enum rpm_status status)
> >         dev->power.runtime_status = status;
> >  }
> >
> > +u64 pm_runtime_accounted_time_get(struct device *dev, enum rpm_status status, bool update)
> > +{
> > +       u64 now = ktime_to_ns(ktime_get());
>
> I think you should stay on jiffies here - and then switch to ktime in patch 3.

I forgot to reply to this comment
Yes I agree that I should stay in jiffies there


>
> > +       u64 delta = 0, time = 0;
> > +       unsigned long flags;
> > +
> > +       spin_lock_irqsave(&dev->power.lock, flags);