From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 083661A0BC4; Thu, 24 Oct 2024 11:47:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729770463; cv=none; b=lU21yv6NyjoWo05S2t171YerxxCrF0eTvz9mQX7HJlMuZHc3j7f1YM5pRaj250NiiBbE+BhMtdSLH79BXsJVuXjH5pWTzv7FHFkjn0G8eUos4Rs59LPkajPl881JANaXsW7Mos6usE1D+TQyyh7meqpwHIsGHHpa96X+R54utBs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729770463; c=relaxed/simple; bh=QUF9a096ChuHj1D1dJOjUtiqgG7NCW3PPEngQhfxS5k=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=eBC6YKLnGxAhRHet9m813c8m+cGk7qjK4kdzXffnQv6QUIejyZjnWQK0SAnArH2dnmLQhtXsbnDKwyCNNUGylOFVqXYTjgZf6zwOh3CIEZtgq/q5emy+irACv2hpys3z//iaxbMS9GEViOM35l8JxvT21mYbS8goar6v+o/O/Oo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 5CF54339; Thu, 24 Oct 2024 04:48:08 -0700 (PDT) Received: from [10.57.55.74] (unknown [10.57.55.74]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 834DC3F71E; Thu, 24 Oct 2024 04:47:37 -0700 (PDT) Message-ID: <3bbf1762-732b-4040-a3f1-eec575ee005e@arm.com> Date: Thu, 24 Oct 2024 12:48:47 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 09/10] thermal: core: Use trip lists for trip crossing detection To: "Rafael J. Wysocki" Cc: LKML , Linux PM , Daniel Lezcano , Zhang Rui , Srinivas Pandruvada References: <4958885.31r3eYUQgx@rjwysocki.net> <2003443.usQuhbGJ8B@rjwysocki.net> Content-Language: en-US From: Lukasz Luba In-Reply-To: <2003443.usQuhbGJ8B@rjwysocki.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/16/24 12:35, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki > > Modify the thermal core to use three lists of trip points: > > trips_high, containing trips with thresholds strictly above the current > thermal zone temperature, > > trips_reached, containing trips with thresholds at or below the current > zone temperature, > > trips_invalid, containing trips with temperature equal to > THERMAL_ZONE_INVALID, > > where the first two lists are always sorted by the current trip > threshold. > > For each trip in trips_high, there is no mitigation under way and > the trip threshold is equal to its temperature. In turn, for each > trip in trips_reached, there is mitigation under way and the trip > threshold is equal to its low temperature. The trips in trips_invalid, > of course, need not be taken into consideration. > > The idea is to make __thermal_zone_device_update() walk trips_high and > trips_reached instead of walking the entire table of trip points in a > thermal zone. Usually, it will only need to walk a few entries in one > of the lists and check one entry in the other list, depending on the > direction of the zone temperature changes, because crossing many trips > by the zone temperature in one go between two consecutive temperature > checks should be unlikely (if it occurs often, the thermal zone > temperature should probably be checked more often either or there > are too many trips). > > This also helps to eliminate one temporary trip list used for trip > crossing notification (only one temporary list is needed for this > purpose instead of two) and the remaining temporary list may be sorted > by the current trip threshold value, like the trips_reached list, so > the additional notify_temp field in struct thermal_trip_desc is not > necessary any more. > > Moreover, since the trips_reached and trips_high lists are sorted, > the "low" and "high" values needed by thermal_zone_set_trips() can be > determined in a straightforward way by looking at one end of each list. > > Of course, additional work is needed in some places in order to > maintain the ordering of the lists, but it is limited to situations > that should be rare, like updating a trip point temperature or > hysteresis, thermal zone initialization, or system resume. Good point I agree. Even the trips from userspace that Daniel proposed shouldn't impact that design decision IMHO. Any disagreement (or am I missing something)? > > Signed-off-by: Rafael J. Wysocki > --- > drivers/thermal/thermal_core.c | 211 +++++++++++++++++++++++++---------------- > drivers/thermal/thermal_core.h | 7 + > 2 files changed, 136 insertions(+), 82 deletions(-) > > Index: linux-pm/drivers/thermal/thermal_core.h > =================================================================== > --- linux-pm.orig/drivers/thermal/thermal_core.h > +++ linux-pm/drivers/thermal/thermal_core.h > @@ -33,7 +33,6 @@ struct thermal_trip_desc { > struct thermal_trip_attrs trip_attrs; > struct list_head list_node; > struct list_head thermal_instances; > - int notify_temp; > int threshold; > }; > > @@ -78,6 +77,9 @@ struct thermal_governor { > * @device: &struct device for this thermal zone > * @removal: removal completion > * @resume: resume completion > + * @trips_high: trips above the current zone temperature > + * @trips_reached: trips below or at the current zone temperature > + * @trips_invalid: trips with invalid temperature > * @mode: current mode of this thermal zone > * @devdata: private pointer for device private data > * @num_trips: number of trip points the thermal zone supports > @@ -118,6 +120,9 @@ struct thermal_zone_device { > struct completion removal; > struct completion resume; > struct attribute_group trips_attribute_group; > + struct list_head trips_high; > + struct list_head trips_reached; > + struct list_head trips_invalid; > enum thermal_device_mode mode; > void *devdata; > int num_trips; > Index: linux-pm/drivers/thermal/thermal_core.c > =================================================================== > --- linux-pm.orig/drivers/thermal/thermal_core.c > +++ linux-pm/drivers/thermal/thermal_core.c > @@ -421,7 +421,7 @@ static void move_trip_to_sorted_list(str > > /* Assume that the new entry is likely to be the last one. */ > list_for_each_entry_reverse(entry, list, list_node) { > - if (entry->notify_temp <= td->notify_temp) { > + if (entry->threshold <= td->threshold) { > list_add(&td->list_node, &entry->list_node); > return; > } > @@ -429,53 +429,6 @@ static void move_trip_to_sorted_list(str > list_add(&td->list_node, list); > } > > -static void handle_thermal_trip(struct thermal_zone_device *tz, > - struct thermal_trip_desc *td, > - struct list_head *way_up_list, > - struct list_head *way_down_list) > -{ > - const struct thermal_trip *trip = &td->trip; > - int old_threshold; > - > - if (trip->temperature == THERMAL_TEMP_INVALID) > - return; > - > - /* > - * If the trip temperature or hysteresis has been updated recently, > - * the threshold needs to be computed again using the new values. > - * However, its initial value still reflects the old ones and that > - * is what needs to be compared with the previous zone temperature > - * to decide which action to take. > - */ > - old_threshold = td->threshold; > - td->threshold = trip->temperature; > - > - if (tz->last_temperature >= old_threshold && > - tz->last_temperature != THERMAL_TEMP_INIT) { > - /* > - * Mitigation is under way, so it needs to stop if the zone > - * temperature falls below the low temperature of the trip. > - * In that case, the trip temperature becomes the new threshold. > - */ > - if (tz->temperature < trip->temperature - trip->hysteresis) { > - td->notify_temp = trip->temperature - trip->hysteresis; > - move_trip_to_sorted_list(td, way_down_list); > - } else { > - td->threshold -= trip->hysteresis; > - } > - } else if (tz->temperature >= trip->temperature) { > - /* > - * There is no mitigation under way, so it needs to be started > - * if the zone temperature exceeds the trip one. The new > - * threshold is then set to the low temperature of the trip. > - */ > - td->notify_temp = trip->temperature; > - move_trip_to_sorted_list(td, way_up_list); > - > - td->threshold -= trip->hysteresis; > - } > -} > - > static void thermal_zone_device_check(struct work_struct *work) > { > struct thermal_zone_device *tz = container_of(work, struct > @@ -484,9 +437,30 @@ static void thermal_zone_device_check(st > thermal_zone_device_update(tz, THERMAL_EVENT_UNSPECIFIED); > } > > +static void move_to_trips_high(struct thermal_zone_device *tz, > + struct thermal_trip_desc *td) > +{ > + td->threshold = td->trip.temperature; > + move_trip_to_sorted_list(td, &tz->trips_high); > +} > + > +static void move_to_trips_reached(struct thermal_zone_device *tz, > + struct thermal_trip_desc *td) > +{ > + td->threshold = td->trip.temperature - td->trip.hysteresis; > + move_trip_to_sorted_list(td, &tz->trips_reached); > +} > + > +static void move_to_trips_invalid(struct thermal_zone_device *tz, > + struct thermal_trip_desc *td) > +{ > + td->threshold = INT_MAX; > + list_move(&td->list_node, &tz->trips_invalid); > +} > + > static void thermal_zone_device_init(struct thermal_zone_device *tz) > { > - struct thermal_trip_desc *td; > + struct thermal_trip_desc *td, *next; > > INIT_DELAYED_WORK(&tz->poll_queue, thermal_zone_device_check); > > @@ -500,6 +474,21 @@ static void thermal_zone_device_init(str > list_for_each_entry(instance, &td->thermal_instances, trip_node) > instance->initialized = false; > } > + /* > + * At this point, all valid trips need to be moved to trips_high so that > + * mitigation can be started if the zone temperature is above them. > + */ > + list_for_each_entry_safe(td, next, &tz->trips_invalid, list_node) { > + if (td->trip.temperature != THERMAL_TEMP_INVALID) > + move_to_trips_high(tz, td); > + } > + /* The trips_reached list may not be empty during system resume. */ > + list_for_each_entry_safe(td, next, &tz->trips_reached, list_node) { > + if (td->trip.temperature == THERMAL_TEMP_INVALID) > + move_to_trips_invalid(tz, td); > + else > + move_to_trips_high(tz, td); > + } > } > > static void thermal_governor_trip_crossed(struct thermal_governor *governor, > @@ -544,45 +533,120 @@ static void thermal_trip_crossed(struct > void thermal_zone_set_trip_hyst(struct thermal_zone_device *tz, > struct thermal_trip *trip, int hyst) > { > + struct thermal_trip_desc *td = trip_to_trip_desc(trip); > + > WRITE_ONCE(trip->hysteresis, hyst); > thermal_notify_tz_trip_change(tz, trip); > + /* > + * If the zone temperature is above or at the trip tmperature, the trip > + * is in the trips_reached list and its threshold is equal to its low > + * temperature. It needs to stay in that list, but its threshold needs > + * to be updated and the list ordering may need to be restored. > + */ > + if (tz->temperature >= td->threshold) > + move_to_trips_reached(tz, td); > } > > void thermal_zone_set_trip_temp(struct thermal_zone_device *tz, > struct thermal_trip *trip, int temp) > { > - if (trip->temperature == temp) > + struct thermal_trip_desc *td = trip_to_trip_desc(trip); > + int old_temp = trip->temperature; > + > + if (old_temp == temp) > return; > > WRITE_ONCE(trip->temperature, temp); > thermal_notify_tz_trip_change(tz, trip); > > - if (temp == THERMAL_TEMP_INVALID) { > - struct thermal_trip_desc *td = trip_to_trip_desc(trip); > + if (old_temp == THERMAL_TEMP_INVALID) { > + /* > + * The trip was invalid before the change, so move it to the > + * trips_high list regardless of the new temperature value > + * because there is no mitigation under way for it. If a > + * mitigation needs to be started, the trip will be moved to the > + * trips_reached list later. > + */ Good comment > + move_to_trips_high(tz, td); > + return; > + } > > + if (temp == THERMAL_TEMP_INVALID) { > /* > - * If the trip has been crossed on the way up, some adjustments > - * are needed to compensate for the lack of it going forward. > + * If the trip is in the trips_reached list, mitigation is under > + * way for it and it needs to be stopped because the trip is > + * effectively going away. > */ > if (tz->temperature >= td->threshold) > thermal_trip_crossed(tz, td, thermal_get_tz_governor(tz), false); > > + move_to_trips_invalid(tz, td); > + return; > + } > + > + /* > + * The trip stays on its current list, but its threshold needs to be > + * updated due to the temperature change and the list ordering may need > + * to be restored. > + */ > + if (tz->temperature >= td->threshold) > + move_to_trips_reached(tz, td); > + else > + move_to_trips_high(tz, td); > +} > +EXPORT_SYMBOL_GPL(thermal_zone_set_trip_temp); > + > +static void thermal_zone_handle_trips(struct thermal_zone_device *tz, > + struct thermal_governor *governor, > + int *low, int *high) > +{ > + struct thermal_trip_desc *td, *next; > + LIST_HEAD(way_down_list); > + > + /* Check the trips that were below or at the zone temperature. */ > + list_for_each_entry_safe_reverse(td, next, &tz->trips_reached, list_node) { > + if (td->threshold <= tz->temperature) > + break; > + > + thermal_trip_crossed(tz, td, governor, false); > /* > - * Invalidate the threshold to avoid triggering a spurious > - * trip crossing notification when the trip becomes valid. > + * The current trips_high list needs to be processed before > + * adding new entries to it, so put them on a temporary list. > */ > - td->threshold = INT_MAX; > + list_move(&td->list_node, &way_down_list); > + } > + /* Check the trips that were previously above the zone temperature. */ > + list_for_each_entry_safe(td, next, &tz->trips_high, list_node) { > + if (td->threshold > tz->temperature) > + break; > + > + thermal_trip_crossed(tz, td, governor, true); > + move_to_trips_reached(tz, td); > + } nit: I would add and extra empty line here, since this is quite separate from the loop above and has important meaning. > + list_for_each_entry_safe(td, next, &way_down_list, list_node) > + move_to_trips_high(tz, td); > + > + if (!list_empty(&tz->trips_reached)) { > + td = list_last_entry(&tz->trips_reached, > + struct thermal_trip_desc, list_node); > + /* > + * Set the "low" value below the current trip threshold in case > + * the zone temperature is at that threshold and stays there, > + * which would trigger a new interrupt immediately in vain. > + */ > + *low = td->threshold - 1; > + } > + if (!list_empty(&tz->trips_high)) { > + td = list_first_entry(&tz->trips_high, > + struct thermal_trip_desc, list_node); > + *high = td->threshold; > } > } > -EXPORT_SYMBOL_GPL(thermal_zone_set_trip_temp); > > void __thermal_zone_device_update(struct thermal_zone_device *tz, > enum thermal_notify_event event) > { > struct thermal_governor *governor = thermal_get_tz_governor(tz); > - struct thermal_trip_desc *td, *next; > - LIST_HEAD(way_down_list); > - LIST_HEAD(way_up_list); > int low = -INT_MAX, high = INT_MAX; > int temp, ret; > > @@ -614,25 +678,7 @@ void __thermal_zone_device_update(struct > > tz->notify_event = event; > > - for_each_trip_desc(tz, td) { > - handle_thermal_trip(tz, td, &way_up_list, &way_down_list); > - > - if (td->threshold <= tz->temperature && td->threshold > low) > - low = td->threshold; > - > - if (td->threshold >= tz->temperature && td->threshold < high) > - high = td->threshold; > - } > - > - list_for_each_entry_safe(td, next, &way_up_list, list_node) { > - thermal_trip_crossed(tz, td, governor, true); > - list_del_init(&td->list_node); > - } > - > - list_for_each_entry_safe_reverse(td, next, &way_down_list, list_node) { > - thermal_trip_crossed(tz, td, governor, false); > - list_del_init(&td->list_node); > - } > + thermal_zone_handle_trips(tz, governor, &low, &high); > > thermal_thresholds_handle(tz, &low, &high); > > @@ -1507,6 +1553,9 @@ thermal_zone_device_register_with_trips( > } > > INIT_LIST_HEAD(&tz->node); > + INIT_LIST_HEAD(&tz->trips_high); > + INIT_LIST_HEAD(&tz->trips_reached); > + INIT_LIST_HEAD(&tz->trips_invalid); > ida_init(&tz->ida); > mutex_init(&tz->lock); > init_completion(&tz->removal); > @@ -1536,7 +1585,7 @@ thermal_zone_device_register_with_trips( > * this only matters for the trips that start as invalid and > * become valid later. > */ > - td->threshold = INT_MAX; > + move_to_trips_invalid(tz, td); > } > > tz->polling_delay_jiffies = msecs_to_jiffies(polling_delay); > > > It took me a while to get the new code flow and idea. Anyway, not that much controversial changes, which might look like, on the first glance, LGTM. Reviewed-by: Lukasz Luba