Re: [PATCH v5 3/3] PM/runtime:Replace jiffies based accounting with ktime based accounting

[Ulf Hansson]

On Fri, 21 Dec 2018 at 11:34, Vincent Guittot
<vincent.guittot@xxxxxxxxxx> wrote:
>
> From: Thara Gopinath <thara.gopinath@xxxxxxxxxx>
>
> This patch replaces jiffies based accounting for runtime_active_time
> and runtime_suspended_time with ktime base accounting. This makes the
> runtime debug counters inline with genpd and other pm subsytems which
> uses ktime based accounting.
>
> timekeeping is initialized before pm_runtime_init() so ktime_get() will
> be ready before first call. In fact, timekeeping_init() is called early
> in start_kernel() which is way before driver_init() (and that's when
> devices can start to be initialized) called from rest_init() via
> kernel_init_freeable() and do_basic_setup().
>
> Signed-off-by: Thara Gopinath <thara.gopinath@xxxxxxxxxx>
> [move from ktime to raw nsec]
> Signed-off-by: Vincent Guittot <vincent.guittot@xxxxxxxxxx>

Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>

Kind regards
Uffe

> ---
>  drivers/base/power/runtime.c | 17 +++++++++--------
>  drivers/base/power/sysfs.c   | 11 ++++++++---
>  include/linux/pm.h           |  6 +++---
>  3 files changed, 20 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
> index e695544..f700524 100644
> --- a/drivers/base/power/runtime.c
> +++ b/drivers/base/power/runtime.c
> @@ -64,8 +64,8 @@ static int rpm_suspend(struct device *dev, int rpmflags);
>   */
>  void update_pm_runtime_accounting(struct device *dev)
>  {
> -       unsigned long now = jiffies;
> -       unsigned long delta;
> +       u64 now = ktime_to_ns(ktime_get());
> +       u64 delta;
>
>         delta = now - dev->power.accounting_timestamp;
>
> @@ -75,9 +75,9 @@ void update_pm_runtime_accounting(struct device *dev)
>                 return;
>
>         if (dev->power.runtime_status == RPM_SUSPENDED)
> -               dev->power.suspended_jiffies += delta;
> +               dev->power.suspended_time += delta;
>         else
> -               dev->power.active_jiffies += delta;
> +               dev->power.active_time += delta;
>  }
>
>  static void __update_runtime_status(struct device *dev, enum rpm_status status)
> @@ -88,17 +88,18 @@ static void __update_runtime_status(struct device *dev, enum rpm_status status)
>
>  u64 pm_runtime_suspended_time(struct device *dev)
>  {
> -       unsigned long flags, time;
> +       u64 time;
> +       unsigned long flags;
>
>         spin_lock_irqsave(&dev->power.lock, flags);
>
>         update_pm_runtime_accounting(dev);
>
> -       time = dev->power.suspended_jiffies;
> +       time = dev->power.suspended_time;
>
>         spin_unlock_irqrestore(&dev->power.lock, flags);
>
> -       return jiffies_to_nsecs(time);
> +       return time;
>  }
>  EXPORT_SYMBOL_GPL(pm_runtime_suspended_time);
>
> @@ -1503,7 +1504,7 @@ void pm_runtime_init(struct device *dev)
>         dev->power.request_pending = false;
>         dev->power.request = RPM_REQ_NONE;
>         dev->power.deferred_resume = false;
> -       dev->power.accounting_timestamp = jiffies;
> +       dev->power.accounting_timestamp = ktime_to_ns(ktime_get());
>         INIT_WORK(&dev->power.work, pm_runtime_work);
>
>         dev->power.timer_expires = 0;
> diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
> index d713738..96c8a22 100644
> --- a/drivers/base/power/sysfs.c
> +++ b/drivers/base/power/sysfs.c
> @@ -125,9 +125,12 @@ static ssize_t runtime_active_time_show(struct device *dev,
>                                 struct device_attribute *attr, char *buf)
>  {
>         int ret;
> +       u64 tmp;
>         spin_lock_irq(&dev->power.lock);
>         update_pm_runtime_accounting(dev);
> -       ret = sprintf(buf, "%i\n", jiffies_to_msecs(dev->power.active_jiffies));
> +       tmp = dev->power.active_time;
> +       do_div(tmp, NSEC_PER_MSEC);
> +       ret = sprintf(buf, "%llu\n", tmp);
>         spin_unlock_irq(&dev->power.lock);
>         return ret;
>  }
> @@ -138,10 +141,12 @@ static ssize_t runtime_suspended_time_show(struct device *dev,
>                                 struct device_attribute *attr, char *buf)
>  {
>         int ret;
> +       u64 tmp;
>         spin_lock_irq(&dev->power.lock);
>         update_pm_runtime_accounting(dev);
> -       ret = sprintf(buf, "%i\n",
> -               jiffies_to_msecs(dev->power.suspended_jiffies));
> +       tmp = dev->power.suspended_time;
> +       do_div(tmp, NSEC_PER_MSEC);
> +       ret = sprintf(buf, "%llu\n", tmp);
>         spin_unlock_irq(&dev->power.lock);
>         return ret;
>  }
> diff --git a/include/linux/pm.h b/include/linux/pm.h
> index e723b78..e5a34e2 100644
> --- a/include/linux/pm.h
> +++ b/include/linux/pm.h
> @@ -632,9 +632,9 @@ struct dev_pm_info {
>         int                     runtime_error;
>         int                     autosuspend_delay;
>         unsigned long           last_busy;
> -       unsigned long           active_jiffies;
> -       unsigned long           suspended_jiffies;
> -       unsigned long           accounting_timestamp;
> +       u64                     active_time;
> +       u64                     suspended_time;
> +       u64                     accounting_timestamp;
>  #endif
>         struct pm_subsys_data   *subsys_data;  /* Owned by the subsystem. */
>         void (*set_latency_tolerance)(struct device *, s32);
> --
> 2.7.4
>