Re: [PATCH 1/2] PM / Domains: Add time accounting to various genpd states.

[Thara Gopinath <thara.gopinath@linaro.org>]

On 06/07/2017 09:28 AM, Ulf Hansson wrote:
Hello Ulf,

> On 26 May 2017 at 01:51, Thara Gopinath <thara.gopinath@linaro.org> wrote:
>> This patch adds support to calculate the time spent by the generic
>> power domains in on and various idle states.
>>
>> Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org>
>> ---
>>  drivers/base/power/domain.c | 24 ++++++++++++++++++++++++
>>  include/linux/pm_domain.h   |  4 ++++
>>  2 files changed, 28 insertions(+)
>>
>> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
>> index da49a83..e733796 100644
>> --- a/drivers/base/power/domain.c
>> +++ b/drivers/base/power/domain.c
>> @@ -207,6 +207,25 @@ static void genpd_sd_counter_inc(struct generic_pm_domain *genpd)
>>         smp_mb__after_atomic();
>>  }
>>
>> +static void genpd_update_accounting(struct generic_pm_domain *genpd)
> 
> I suggest we have all this within #ifdef CONFIG_DEBUG_FS and add a
> stub for !CONFIG_DEBUG_FS.
> 
>> +{
>> +       ktime_t delta, now;
>> +
>> +       now = ktime_get();
>> +       delta = ktime_sub(now, genpd->accounting_time);
>> +
>> +       if (genpd->status == GPD_STATE_ACTIVE) {
>> +               genpd->on_time = ktime_add(genpd->on_time, delta);
>> +       } else {
>> +               int state_idx = genpd->state_idx;
>> +
>> +               genpd->states[state_idx].active_time =
> 
> "active_time" seems to be a misleading, can we rename it to "idle_time" instead?
> 
>> +                       ktime_add(genpd->states[state_idx].active_time, delta);
>> +               genpd->off_time = ktime_add(genpd->off_time, delta);
> 
> Isn't the off_time the summary of the states' genpd->states[i].active_time?
> 
> Then we could do that computation quite easily at the point when
> producing the debugfs output instead.
> 
>> +       }
>> +       genpd->accounting_time = now;
>> +}
>> +
>>  static int _genpd_power_on(struct generic_pm_domain *genpd, bool timed)
>>  {
>>         unsigned int state_idx = genpd->state_idx;
>> @@ -358,6 +377,7 @@ static int genpd_power_off(struct generic_pm_domain *genpd, bool one_dev_on,
>>                         return ret;
>>         }
>>
>> +       genpd_update_accounting(genpd);
> 
> It find it a bit odd to update accounting just before changing the
> status. Can we re-work this and update accounting right afterwards
> instead? At least to me, that makes this easier to understand.

The accounting is being updated for the previous state and not the
current state. For eg if the domain has been previously off and just
turned on, the time spent in off state is updated. So it
upadte_accounting has to be before changing the status.
Sorry I did not mention this earlier as I just realized this as
I was reworking the patches.

Regards
Thara
> 
>>         genpd->status = GPD_STATE_POWER_OFF;
>>
>>         list_for_each_entry(link, &genpd->slave_links, slave_node) {
>> @@ -410,6 +430,7 @@ static int genpd_power_on(struct generic_pm_domain *genpd, unsigned int depth)
>>         if (ret)
>>                 goto err;
>>
>> +       genpd_update_accounting(genpd);
> 
> Ditto.
> 
>>         genpd->status = GPD_STATE_ACTIVE;
>>         return 0;
>>
>> @@ -774,6 +795,7 @@ static void genpd_sync_power_off(struct generic_pm_domain *genpd, bool use_lock,
>>         if (_genpd_power_off(genpd, false))
>>                 return;
>>
>> +       genpd_update_accounting(genpd);
> 
> Timekeeping gets disabled at a certain point during suspend. Therefore
> you can't update accounting here, as this function gets called in this
> stages.
> 
>>         genpd->status = GPD_STATE_POWER_OFF;
>>
>>         list_for_each_entry(link, &genpd->slave_links, slave_node) {
>> @@ -821,6 +843,7 @@ static void genpd_sync_power_on(struct generic_pm_domain *genpd, bool use_lock,
>>
>>         _genpd_power_on(genpd, false);
>>
>> +       genpd_update_accounting(genpd);
> 
> Ditto.
> 
>>         genpd->status = GPD_STATE_ACTIVE;
>>  }
>>
>> @@ -1486,6 +1509,7 @@ int pm_genpd_init(struct generic_pm_domain *genpd,
>>         genpd->max_off_time_changed = true;
>>         genpd->provider = NULL;
>>         genpd->has_provider = false;
>> +       genpd->accounting_time = ktime_get();
>>         genpd->domain.ops.runtime_suspend = genpd_runtime_suspend;
>>         genpd->domain.ops.runtime_resume = genpd_runtime_resume;
>>         genpd->domain.ops.prepare = pm_genpd_prepare;
>> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
>> index b7803a2..8bee0e3 100644
>> --- a/include/linux/pm_domain.h
>> +++ b/include/linux/pm_domain.h
>> @@ -43,6 +43,7 @@ struct genpd_power_state {
>>         s64 power_on_latency_ns;
>>         s64 residency_ns;
>>         struct fwnode_handle *fwnode;
>> +       ktime_t active_time;
>>  };
>>
>>  struct genpd_lock_ops;
>> @@ -78,6 +79,9 @@ struct generic_pm_domain {
>>         unsigned int state_count; /* number of states */
>>         unsigned int state_idx; /* state that genpd will go to when off */
>>         void *free; /* Free the state that was allocated for default */
>> +       ktime_t on_time;
>> +       ktime_t off_time;
>> +       ktime_t accounting_time;
>>         const struct genpd_lock_ops *lock_ops;
>>         union {
>>                 struct mutex mlock;
>> --
>> 2.1.4
>>
> 
> Kind regards
> Uffe
> 


-- 
Regards
Thara