Re: [Intel-gfx] [PATCH v4 3/3] PM/runtime:Replace jiffies based accounting with ktime based accounting
Hi Rafael,
On Fri, 21 Dec 2018 at 09:58, Rafael J. Wysocki wrote:
>
> On Thu, Dec 20, 2018 at 11:03 PM Ulf Hansson wrote:
> >
> > On Thu, 20 Dec 2018 at 15:17, Vincent Guittot
> > wrote:
> > >
> > > From: Thara Gopinath
> > >
> > > 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.
> > >
> > > Signed-off-by: Thara Gopinath
> > > [move from ktime to raw nsec]
> > > Signed-off-by: Vincent Guittot
> > > ---
> > > 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(>power.lock, flags);
> > >
> > > update_pm_runtime_accounting(dev);
> > >
> > > - time = dev->power.suspended_jiffies;
> > > + time = dev->power.suspended_time;
> > >
> > > spin_unlock_irqrestore(>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());
> >
> > This change worries me a bit, but it may not be a problem in practice.
> >
> > pm_runtime_init() is called when devices get initialized, via
> > device_initialize(). If timekeeping has not been initialized prior a
> > call to ktime_get() is done, it will fail and causing a NULL pointer
> > deference or something along those lines.
> >
> > In other words, do we know that device_initialize() is always called
> > after timekeeping has been initialized during boot?
>
> We do.
>
> 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().
Thanks for the confirmation. I'm going to add your answer in the
commit message so we will have the answer next time someone will
wonder
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Re: [Intel-gfx] [PATCH v4 3/3] PM/runtime:Replace jiffies based accounting with ktime based accounting
On Thu, Dec 20, 2018 at 11:03 PM Ulf Hansson wrote:
>
> On Thu, 20 Dec 2018 at 15:17, Vincent Guittot
> wrote:
> >
> > From: Thara Gopinath
> >
> > 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.
> >
> > Signed-off-by: Thara Gopinath
> > [move from ktime to raw nsec]
> > Signed-off-by: Vincent Guittot
> > ---
> > 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(>power.lock, flags);
> >
> > update_pm_runtime_accounting(dev);
> >
> > - time = dev->power.suspended_jiffies;
> > + time = dev->power.suspended_time;
> >
> > spin_unlock_irqrestore(>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());
>
> This change worries me a bit, but it may not be a problem in practice.
>
> pm_runtime_init() is called when devices get initialized, via
> device_initialize(). If timekeeping has not been initialized prior a
> call to ktime_get() is done, it will fail and causing a NULL pointer
> deference or something along those lines.
>
> In other words, do we know that device_initialize() is always called
> after timekeeping has been initialized during boot?
We do.
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().
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Re: [Intel-gfx] [PATCH v4 3/3] PM/runtime:Replace jiffies based accounting with ktime based accounting
On Thu, 20 Dec 2018 at 23:03, Ulf Hansson wrote:
>
> On Thu, 20 Dec 2018 at 15:17, Vincent Guittot
> wrote:
> >
> > From: Thara Gopinath
> >
> > 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.
> >
> > Signed-off-by: Thara Gopinath
> > [move from ktime to raw nsec]
> > Signed-off-by: Vincent Guittot
> > ---
> > 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(>power.lock, flags);
> >
> > update_pm_runtime_accounting(dev);
> >
> > - time = dev->power.suspended_jiffies;
> > + time = dev->power.suspended_time;
> >
> > spin_unlock_irqrestore(>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());
>
> This change worries me a bit, but it may not be a problem in practice.
>
> pm_runtime_init() is called when devices get initialized, via
> device_initialize(). If timekeeping has not been initialized prior a
> call to ktime_get() is done, it will fail and causing a NULL pointer
> deference or something along those lines.
>
> In other words, do we know that device_initialize() is always called
> after timekeeping has been initialized during boot?
That something we discussed at lpc and we should be safe
>
> [...]
>
> Kind regards
> Uffe
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Re: [Intel-gfx] [PATCH v4 3/3] PM/runtime:Replace jiffies based accounting with ktime based accounting
On Thu, 20 Dec 2018 at 15:17, Vincent Guittot
wrote:
>
> From: Thara Gopinath
>
> 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.
>
> Signed-off-by: Thara Gopinath
> [move from ktime to raw nsec]
> Signed-off-by: Vincent Guittot
> ---
> 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(>power.lock, flags);
>
> update_pm_runtime_accounting(dev);
>
> - time = dev->power.suspended_jiffies;
> + time = dev->power.suspended_time;
>
> spin_unlock_irqrestore(>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());
This change worries me a bit, but it may not be a problem in practice.
pm_runtime_init() is called when devices get initialized, via
device_initialize(). If timekeeping has not been initialized prior a
call to ktime_get() is done, it will fail and causing a NULL pointer
deference or something along those lines.
In other words, do we know that device_initialize() is always called
after timekeeping has been initialized during boot?
[...]
Kind regards
Uffe
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