From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752780AbbHKRhU (ORCPT ); Tue, 11 Aug 2015 13:37:20 -0400 Received: from fw-tnat.cambridge.arm.com ([217.140.96.140]:38548 "EHLO cam-smtp0.cambridge.arm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751672AbbHKRhS (ORCPT ); Tue, 11 Aug 2015 13:37:18 -0400 Date: Tue, 11 Aug 2015 18:37:11 +0100 From: Javi Merino To: Punit Agrawal Cc: "linux-pm@vger.kernel.org" , "dmitry.torokhov@gmail.com" , "cywang@chromium.org" , "linux-kernel@vger.kernel.org" , Zhang Rui , Eduardo Valentin Subject: Re: [PATCH v2 1/4] thermal: power_allocator: relax the requirement of a sustainable_power in tzp Message-ID: <20150811173711.GA9024@e104805> References: <1439222692-3535-1-git-send-email-javi.merino@arm.com> <1439288493-19740-1-git-send-email-javi.merino@arm.com> <1439288493-19740-2-git-send-email-javi.merino@arm.com> <9hhegjakklf.fsf@e105922-lin.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <9hhegjakklf.fsf@e105922-lin.cambridge.arm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 11, 2015 at 02:42:20PM +0100, Punit Agrawal wrote: > Hi Javi, > > A few nitpicks and a comment below. > > Javi Merino writes: > > > The power allocator governor currently requires that a sustainable power > > is passed as part of the thermal zone's thermal zone parameters. If > > that parameter is not provided, it doesn't register with the thermal > > zone. > > > > While this parameter is strongly recommended for optimal performance, it > > doesn't need to be mandatory. Relax the requirement and allow the > > governor to bind to thermal zones that don't provide it by estimating it > > from the cooling devices' power model. > > > > Cc: Zhang Rui > > Cc: Eduardo Valentin > > Signed-off-by: Javi Merino > > --- > > drivers/thermal/power_allocator.c | 62 +++++++++++++++++++++++++++++++++------ > > drivers/thermal/thermal_core.c | 28 ++++++++++++++++++ > > include/linux/thermal.h | 6 ++++ > > 3 files changed, 87 insertions(+), 9 deletions(-) > > > > diff --git a/drivers/thermal/power_allocator.c b/drivers/thermal/power_allocator.c > > index 63a448f9d93b..f78836c2da26 100644 > > --- a/drivers/thermal/power_allocator.c > > +++ b/drivers/thermal/power_allocator.c > > @@ -73,6 +73,39 @@ struct power_allocator_params { > > }; > > > > /** > > + * estimate_sustainable_power() - Estimate the sustainable power of a thermal zone > > + * @tz: thermal zone we are operating in > > + * > > + * For thermal zones that don't provide a sustainable_power in their > > + * thermal_zone_params, estimate one. Calculate it using the minimum > > + * power of all the cooling devices as that gives a valid value that > > + * can give some degree of functionality. For optimal performance of > > + * this governor, provide a sustainable_power in the thermal zone's > > + * thermal_zone_params. > > + */ > > +static u32 estimate_sustainable_power(struct thermal_zone_device *tz) > > +{ > > + u32 sustainable_power = 0; > > + struct thermal_instance *instance; > > + struct power_allocator_params *params = tz->governor_data; > > + > > + list_for_each_entry(instance, &tz->thermal_instances, tz_node) { > > + struct thermal_cooling_device *cdev = instance->cdev; > > + u32 min_power; > > + > > + if (instance->trip != params->trip_max_desired_temperature) > > + continue; > > + > > + if (power_actor_get_min_power(cdev, tz, &min_power)) > > + continue; > > + > > + sustainable_power += min_power; > > + } > > + > > + return sustainable_power; > > +} > > + > > +/** > > * pid_controller() - PID controller > > * @tz: thermal zone we are operating in > > * @current_temp: the current temperature in millicelsius > > @@ -98,6 +131,7 @@ static u32 pid_controller(struct thermal_zone_device *tz, > > { > > s64 p, i, d, power_range; > > s32 err, max_power_frac; > > + u32 sustainable_power; > > struct power_allocator_params *params = tz->governor_data; > > > > max_power_frac = int_to_frac(max_allocatable_power); > > @@ -138,8 +172,11 @@ static u32 pid_controller(struct thermal_zone_device *tz, > > > > power_range = p + i + d; > > > > + sustainable_power = tz->tzp->sustainable_power ?: > > + estimate_sustainable_power(tz); > > + > > /* feed-forward the known sustainable dissipatable power */ > > - power_range = tz->tzp->sustainable_power + frac_to_int(power_range); > > + power_range = sustainable_power + frac_to_int(power_range); > > > > power_range = clamp(power_range, (s64)0, (s64)max_allocatable_power); > > > > @@ -418,18 +455,18 @@ static int power_allocator_bind(struct thermal_zone_device *tz) > > int ret; > > struct power_allocator_params *params; > > unsigned long switch_on_temp, control_temp; > > - u32 temperature_threshold; > > + u32 sustainable_power, temperature_threshold; > > > > - if (!tz->tzp || !tz->tzp->sustainable_power) { > > - dev_err(&tz->device, > > - "power_allocator: missing sustainable_power\n"); > > + if (!tz->tzp) > > return -EINVAL; > > - } > > > > params = devm_kzalloc(&tz->device, sizeof(*params), GFP_KERNEL); > > if (!params) > > return -ENOMEM; > > > > + if (!tz->tzp->sustainable_power) > > + dev_warn(&tz->device, "power_allocator: sustainable_power will be estimated\n"); > > + > > ret = get_governor_trips(tz, params); > > if (ret) { > > dev_err(&tz->device, > > @@ -448,13 +485,20 @@ static int power_allocator_bind(struct thermal_zone_device *tz) > > if (ret) > > goto free; > > > > + /* > > + * Provide an arbitrary sustainable_power to set the default > > + * values of k_po and k_pu. We can estimate sustainable_power > ^ > can not > > + * at this point because no cooling devices have been > > + * registered yet. By providing an arbitrary value we get > > + * better defaults that setting k_po and k_pu to 0. > ^ > than Fixed both. > > + */ > > + sustainable_power = tz->tzp->sustainable_power ?: 2500; > > temperature_threshold = control_temp - switch_on_temp; > > > > tz->tzp->k_po = tz->tzp->k_po ?: > > - int_to_frac(tz->tzp->sustainable_power) / temperature_threshold; > > + int_to_frac(sustainable_power) / temperature_threshold; > > tz->tzp->k_pu = tz->tzp->k_pu ?: > > - int_to_frac(2 * tz->tzp->sustainable_power) / > > - temperature_threshold; > > + int_to_frac(2 * sustainable_power) / temperature_threshold; > > As we are being conservative with our estimation of sustainable power > (sum of mins) when it is not explicitly specified, should we be > conservative here and let the proportional terms, k_po and k_pu be zero > as well? Yes, we could do. If we set it to zero, all cooling devices will be set to the maximum cooling state when the governor is active. If we set it to a valid(ish) value, it will do a bit of thermal control. It's not perfect but I think it's better to have a bad estimate than no estimate. > > tz->tzp->k_i = tz->tzp->k_i ?: int_to_frac(10) / 1000; > > /* > > * The default for k_d and integral_cutoff is 0, so we can > > diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c > > index 4ca211be4c0f..d26bc9e6f936 100644 > > --- a/drivers/thermal/thermal_core.c > > +++ b/drivers/thermal/thermal_core.c > > @@ -997,6 +997,34 @@ int power_actor_get_max_power(struct thermal_cooling_device *cdev, > > } > > > > /** > > + * power_actor_get_min_power() - get the mainimum power that a cdev can consume > > + * @cdev: pointer to &thermal_cooling_device > > + * @tz: a valid thermal zone device pointer > > + * @min_power: pointer in which to store the minimum power > > + * > > + * Calculate the minimum power consumption in milliwats that the > > + * cooling device can currently consume and store it in @min_power. > > + * > > + * Return: 0 on success, -EINVAL if @cdev doesn't support the > > + * power_actor API or -E* on other error. > > + */ > > +int power_actor_get_min_power(struct thermal_cooling_device *cdev, > > + struct thermal_zone_device *tz, u32 *min_power) > > +{ > > + unsigned long max_state; > > + int ret; > > + > > + if (!cdev_is_power_actor(cdev)) > > + return -EINVAL; > > + > > + ret = cdev->ops->get_max_state(cdev, &max_state); > > + if (ret) > > + return ret; > > + > > + return cdev->ops->state2power(cdev, tz, max_state, min_power); > > +} > > + > > +/** > > * power_actor_set_power() - limit the maximum power that a cooling device can consume > > * @cdev: pointer to &thermal_cooling_device > > * @instance: thermal instance to update > > diff --git a/include/linux/thermal.h b/include/linux/thermal.h > > index 037e9df2f610..f99d934d373a 100644 > > --- a/include/linux/thermal.h > > +++ b/include/linux/thermal.h > > @@ -384,6 +384,8 @@ static inline bool cdev_is_power_actor(struct thermal_cooling_device *cdev) > > > > int power_actor_get_max_power(struct thermal_cooling_device *, > > struct thermal_zone_device *tz, u32 *max_power); > > +int power_actor_get_min_power(struct thermal_cooling_device *, > > + struct thermal_zone_device *tz, u32 *min_power); > > int power_actor_set_power(struct thermal_cooling_device *, > > struct thermal_instance *, u32); > > struct thermal_zone_device *thermal_zone_device_register(const char *, int, int, > > @@ -419,6 +421,10 @@ static inline bool cdev_is_power_actor(struct thermal_cooling_device *cdev) > > static inline int power_actor_get_max_power(struct thermal_cooling_device *cdev, > > struct thermal_zone_device *tz, u32 *max_power) > > { return 0; } > > +static inline int power_actor_get_min_power(struct thermal_cooling_device *cdev, > > + struct thermal_zone_device *tz, > > + u32 *min_power) > > +{ return -ENODEV; } > > Perhaps return 0 like power_actor_get_max_power just above for > consistency. No, return 0 is not a good idea. If you return 0, you're telling the calling function that everything went all right and you've put the minimum power in @min_power. What we should do is fix power_actor_get_max_power() and power_actor_set_power() to return an error value if !CONFIG_THERMAL. Cheers, Javi