From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E2085EB64D7 for ; Tue, 20 Jun 2023 10:19:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231618AbjFTKTz (ORCPT ); Tue, 20 Jun 2023 06:19:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46430 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232001AbjFTKTv (ORCPT ); Tue, 20 Jun 2023 06:19:51 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 5E883A2; Tue, 20 Jun 2023 03:19:49 -0700 (PDT) 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 ADE501063; Tue, 20 Jun 2023 03:20:32 -0700 (PDT) Received: from [10.57.26.18] (unknown [10.57.26.18]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 11A6D3F64C; Tue, 20 Jun 2023 03:19:46 -0700 (PDT) Message-ID: Date: Tue, 20 Jun 2023 11:20:04 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: [PATCH V4] thermal/core/power_allocator: reset thermal governor when trip point is changed Content-Language: en-US To: "Rafael J. Wysocki" Cc: daniel.lezcano@linaro.org, rui.zhang@intel.com, Di Shen , amitk@kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, xuewen.yan@unisoc.com, jeson.gao@unisoc.com, zhanglyra@gmail.com, orsonzhai@gmail.com References: <6aad180f-410c-5b11-b30b-c7bc02cbe054@linaro.org> <20230619063534.12831-1-di.shen@unisoc.com> From: Lukasz Luba In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Rafael, On 6/20/23 11:07, Rafael J. Wysocki wrote: > On Tue, Jun 20, 2023 at 11:46 AM Rafael J. Wysocki wrote: >> >> On Mon, Jun 19, 2023 at 8:36 AM Di Shen wrote: >>> >>> When the thermal trip point is changed, the governor should >>> be reset so that the policy algorithm be updated to adapt to the >>> new trip point. >>> >>> This patch adds an ops for thermal the governor structure to reset >>> the governor. The ops is called when the trip point is changed. >>> For power allocator, the parameters of pid controller and the states >>> of power cooling devices can be reset when the passive trip point >>> is changed. >>> >>> Signed-off-by: Di Shen >>> >>> --- >>> V4: >>> - Compared to V3, handle it in thermal core instead of in governor. >>> >>> - Add an ops to the governor structure, and call it when a trip >>> point is changed. >>> >>> - Define reset ops for power allocator. >>> >>> V3: >>> - Add fix tag. >>> >>> V2: >>> - Compared to v1, do not revert. >>> >>> - Add a variable(last_switch_on_temp) in power_allocator_params >>> to record the last switch_on_temp value. >>> >>> - Adds a function to renew the update flag and update the >>> last_switch_on_temp when thermal trips are writable. >>> >>> V1: >>> - Revert commit 0952177f2a1f. >>> --- >>> --- >>> drivers/thermal/gov_power_allocator.c | 21 +++++++++++++++++++++ >>> drivers/thermal/thermal_trip.c | 6 ++++++ >>> include/linux/thermal.h | 1 + >>> 3 files changed, 28 insertions(+) >>> >>> diff --git a/drivers/thermal/gov_power_allocator.c b/drivers/thermal/gov_power_allocator.c >>> index 8642f1096b91..41d155adc616 100644 >>> --- a/drivers/thermal/gov_power_allocator.c >>> +++ b/drivers/thermal/gov_power_allocator.c >>> @@ -729,10 +729,31 @@ static int power_allocator_throttle(struct thermal_zone_device *tz, int trip_id) >>> return allocate_power(tz, trip.temperature); >>> } >>> >>> +static int power_allocator_reset(struct thermal_zone_device *tz, int trip_id) >>> +{ >>> + int ret = 0; >>> + struct thermal_trip trip; >>> + struct power_allocator_params *params = tz->governor_data; >>> + >>> + ret = __thermal_zone_get_trip(tz, trip_id, &trip); >>> + if (ret) >>> + return ret; >>> + >>> + /* Only need reset for passive trips */ >>> + if (trip.type != THERMAL_TRIP_PASSIVE) >>> + return -EINVAL; >>> + >>> + reset_pid_controller(params); >>> + allow_maximum_power(tz, true); >>> + >>> + return ret; >>> +} >>> + >>> static struct thermal_governor thermal_gov_power_allocator = { >>> .name = "power_allocator", >>> .bind_to_tz = power_allocator_bind, >>> .unbind_from_tz = power_allocator_unbind, >>> .throttle = power_allocator_throttle, >>> + .reset = power_allocator_reset, >>> }; >>> THERMAL_GOVERNOR_DECLARE(thermal_gov_power_allocator); >>> diff --git a/drivers/thermal/thermal_trip.c b/drivers/thermal/thermal_trip.c >>> index 907f3a4d7bc8..52eb768fada8 100644 >>> --- a/drivers/thermal/thermal_trip.c >>> +++ b/drivers/thermal/thermal_trip.c >>> @@ -173,6 +173,12 @@ int thermal_zone_set_trip(struct thermal_zone_device *tz, int trip_id, >>> if (tz->trips && (t.temperature != trip->temperature || t.hysteresis != trip->hysteresis)) >>> tz->trips[trip_id] = *trip; >>> >>> + if (t.temperature != trip->temperature && tz->governor && tz->governor->reset) { >>> + ret = tz->governor->reset(tz, trip_id); >>> + if (ret) >>> + pr_warn_once("Failed to reset thermal governor\n"); >> >> I'm not really sure if it is useful to print this message here. >> >> First off, the governors may print more precise diagnostic messages if >> they care. >> >> Second, what is the sysadmin supposed to do in response to this message? > > In addition to the above, trip point temperatures may be updated in > other places too, for instance in response to notifications from > platform firmware and IMV this new callback should be also used in > those cases. However, in those cases multiple trip points may change > at a time and the critical/hot trip point temperatures may be updated > too AFAICS. IIRC the critical/hot trip points are handled differently, not using the governors. The governors' 'throttle' callback would be called only after we pass the test of 'critical/hot' [1]. What Di is facing is in the issue under the bucket of 'handle_non_critical_trips()' when the governor just tries to work on stale data - old trip temp. For the 2nd case IIUC the code, we pass the 'trip.temperature' and should be ready for what you said (modification of that value). Furthermore, the critical/hot situation is handled w/o governor assistance, so we should be safe: tz->ops->critical(tz) or tz->ops->hot(tz) and not tz->governor->throttle(tz, trip) Would you agree Rafael? Regards, Lukasz [1] https://elixir.bootlin.com/linux/v6.3/source/drivers/thermal/thermal_core.c#L370