[V2,1/4] powercap/drivers/idle_inject: Specify idle state max latency
diff mbox series

Message ID 20200329220324.8785-1-daniel.lezcano@linaro.org
State New
Delegated to: Daniel Lezcano
Headers show
Series
  • [V2,1/4] powercap/drivers/idle_inject: Specify idle state max latency
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Commit Message

Daniel Lezcano March 29, 2020, 10:03 p.m. UTC
Currently the idle injection framework uses the play_idle() function
which puts the current CPU in an idle state. The idle state is the
deepest one, as specified by the latency constraint when calling the
subsequent play_idle_precise() function with the INT_MAX.

The idle_injection is used by the cpuidle_cooling device which
computes the idle / run duration to mitigate the temperature by
injecting idle cycles. The cooling device has no control on the depth
of the idle state.

Allow finer control of the idle injection mechanism by allowing to
specify the latency for the idle state. Thus the cooling device has
the ability to have a guarantee on the exit latency of the idle states
it is injecting.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
---
  - V2:
    - Remove the get_latency helper

---
 drivers/powercap/idle_inject.c | 16 +++++++++++++++-
 include/linux/idle_inject.h    |  4 ++++
 2 files changed, 19 insertions(+), 1 deletion(-)

Comments

Rafael J. Wysocki April 3, 2020, 9:38 a.m. UTC | #1
On Monday, March 30, 2020 12:03:17 AM CEST Daniel Lezcano wrote:
> Currently the idle injection framework uses the play_idle() function
> which puts the current CPU in an idle state. The idle state is the
> deepest one, as specified by the latency constraint when calling the
> subsequent play_idle_precise() function with the INT_MAX.
> 
> The idle_injection is used by the cpuidle_cooling device which
> computes the idle / run duration to mitigate the temperature by
> injecting idle cycles. The cooling device has no control on the depth
> of the idle state.
> 
> Allow finer control of the idle injection mechanism by allowing to
> specify the latency for the idle state. Thus the cooling device has
> the ability to have a guarantee on the exit latency of the idle states
> it is injecting.
> 
> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

And I'm assuming that you will take care of the series yourself.

> ---
>   - V2:
>     - Remove the get_latency helper
> 
> ---
>  drivers/powercap/idle_inject.c | 16 +++++++++++++++-
>  include/linux/idle_inject.h    |  4 ++++
>  2 files changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/powercap/idle_inject.c b/drivers/powercap/idle_inject.c
> index cd1270614cc6..49f42c475620 100644
> --- a/drivers/powercap/idle_inject.c
> +++ b/drivers/powercap/idle_inject.c
> @@ -61,12 +61,14 @@ struct idle_inject_thread {
>   * @timer: idle injection period timer
>   * @idle_duration_us: duration of CPU idle time to inject
>   * @run_duration_us: duration of CPU run time to allow
> + * @latency_us: max allowed latency
>   * @cpumask: mask of CPUs affected by idle injection
>   */
>  struct idle_inject_device {
>  	struct hrtimer timer;
>  	unsigned int idle_duration_us;
>  	unsigned int run_duration_us;
> +	unsigned int latency_us;
>  	unsigned long int cpumask[0];
>  };
>  
> @@ -138,7 +140,8 @@ static void idle_inject_fn(unsigned int cpu)
>  	 */
>  	iit->should_run = 0;
>  
> -	play_idle(READ_ONCE(ii_dev->idle_duration_us));
> +	play_idle_precise(READ_ONCE(ii_dev->idle_duration_us) * NSEC_PER_USEC,
> +			  READ_ONCE(ii_dev->latency_us) * NSEC_PER_USEC);
>  }
>  
>  /**
> @@ -169,6 +172,16 @@ void idle_inject_get_duration(struct idle_inject_device *ii_dev,
>  	*idle_duration_us = READ_ONCE(ii_dev->idle_duration_us);
>  }
>  
> +/**
> + * idle_inject_set_latency - set the maximum latency allowed
> + * @latency_us: set the latency requirement for the idle state
> + */
> +void idle_inject_set_latency(struct idle_inject_device *ii_dev,
> +			     unsigned int latency_us)
> +{
> +	WRITE_ONCE(ii_dev->latency_us, latency_us);
> +}
> +
>  /**
>   * idle_inject_start - start idle injections
>   * @ii_dev: idle injection control device structure
> @@ -297,6 +310,7 @@ struct idle_inject_device *idle_inject_register(struct cpumask *cpumask)
>  	cpumask_copy(to_cpumask(ii_dev->cpumask), cpumask);
>  	hrtimer_init(&ii_dev->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
>  	ii_dev->timer.function = idle_inject_timer_fn;
> +	ii_dev->latency_us = UINT_MAX;
>  
>  	for_each_cpu(cpu, to_cpumask(ii_dev->cpumask)) {
>  
> diff --git a/include/linux/idle_inject.h b/include/linux/idle_inject.h
> index a445cd1a36c5..91a8612b8bf9 100644
> --- a/include/linux/idle_inject.h
> +++ b/include/linux/idle_inject.h
> @@ -26,4 +26,8 @@ void idle_inject_set_duration(struct idle_inject_device *ii_dev,
>  void idle_inject_get_duration(struct idle_inject_device *ii_dev,
>  				 unsigned int *run_duration_us,
>  				 unsigned int *idle_duration_us);
> +
> +void idle_inject_set_latency(struct idle_inject_device *ii_dev,
> +			     unsigned int latency_ns);
> +
>  #endif /* __IDLE_INJECT_H__ */
>
Daniel Lezcano April 3, 2020, 11:09 a.m. UTC | #2
On 03/04/2020 11:38, Rafael J. Wysocki wrote:
> On Monday, March 30, 2020 12:03:17 AM CEST Daniel Lezcano wrote:
>> Currently the idle injection framework uses the play_idle()
>> function which puts the current CPU in an idle state. The idle
>> state is the deepest one, as specified by the latency constraint
>> when calling the subsequent play_idle_precise() function with the
>> INT_MAX.
>>
>> The idle_injection is used by the cpuidle_cooling device which
>> computes the idle / run duration to mitigate the temperature by
>> injecting idle cycles. The cooling device has no control on the
>> depth of the idle state.
>>
>> Allow finer control of the idle injection mechanism by allowing
>> to specify the latency for the idle state. Thus the cooling
>> device has the ability to have a guarantee on the exit latency of
>> the idle states it is injecting.
>>
>> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
>
> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> And I'm assuming that you will take care of the series yourself.

Yes, thanks for reviewing.

 - Daniel

Patch
diff mbox series

diff --git a/drivers/powercap/idle_inject.c b/drivers/powercap/idle_inject.c
index cd1270614cc6..49f42c475620 100644
--- a/drivers/powercap/idle_inject.c
+++ b/drivers/powercap/idle_inject.c
@@ -61,12 +61,14 @@  struct idle_inject_thread {
  * @timer: idle injection period timer
  * @idle_duration_us: duration of CPU idle time to inject
  * @run_duration_us: duration of CPU run time to allow
+ * @latency_us: max allowed latency
  * @cpumask: mask of CPUs affected by idle injection
  */
 struct idle_inject_device {
 	struct hrtimer timer;
 	unsigned int idle_duration_us;
 	unsigned int run_duration_us;
+	unsigned int latency_us;
 	unsigned long int cpumask[0];
 };
 
@@ -138,7 +140,8 @@  static void idle_inject_fn(unsigned int cpu)
 	 */
 	iit->should_run = 0;
 
-	play_idle(READ_ONCE(ii_dev->idle_duration_us));
+	play_idle_precise(READ_ONCE(ii_dev->idle_duration_us) * NSEC_PER_USEC,
+			  READ_ONCE(ii_dev->latency_us) * NSEC_PER_USEC);
 }
 
 /**
@@ -169,6 +172,16 @@  void idle_inject_get_duration(struct idle_inject_device *ii_dev,
 	*idle_duration_us = READ_ONCE(ii_dev->idle_duration_us);
 }
 
+/**
+ * idle_inject_set_latency - set the maximum latency allowed
+ * @latency_us: set the latency requirement for the idle state
+ */
+void idle_inject_set_latency(struct idle_inject_device *ii_dev,
+			     unsigned int latency_us)
+{
+	WRITE_ONCE(ii_dev->latency_us, latency_us);
+}
+
 /**
  * idle_inject_start - start idle injections
  * @ii_dev: idle injection control device structure
@@ -297,6 +310,7 @@  struct idle_inject_device *idle_inject_register(struct cpumask *cpumask)
 	cpumask_copy(to_cpumask(ii_dev->cpumask), cpumask);
 	hrtimer_init(&ii_dev->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 	ii_dev->timer.function = idle_inject_timer_fn;
+	ii_dev->latency_us = UINT_MAX;
 
 	for_each_cpu(cpu, to_cpumask(ii_dev->cpumask)) {
 
diff --git a/include/linux/idle_inject.h b/include/linux/idle_inject.h
index a445cd1a36c5..91a8612b8bf9 100644
--- a/include/linux/idle_inject.h
+++ b/include/linux/idle_inject.h
@@ -26,4 +26,8 @@  void idle_inject_set_duration(struct idle_inject_device *ii_dev,
 void idle_inject_get_duration(struct idle_inject_device *ii_dev,
 				 unsigned int *run_duration_us,
 				 unsigned int *idle_duration_us);
+
+void idle_inject_set_latency(struct idle_inject_device *ii_dev,
+			     unsigned int latency_ns);
+
 #endif /* __IDLE_INJECT_H__ */