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([2a05:6e02:1041:c10:4b66:e1c1:7cd0:485e]) by smtp.googlemail.com with ESMTPSA id v7-20020a05600c214700b003f4f89bc48dsm1455679wml.15.2023.05.24.01.06.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 24 May 2023 01:06:31 -0700 (PDT) Message-ID: <745b8b17-af4d-e8e1-83c1-89d600e7cd19@linaro.org> Date: Wed, 24 May 2023 10:06:30 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 Subject: Re: [CfP] Power Management and Thermal Control MC (LPC2023) Content-Language: en-US To: "Rafael J. Wysocki" , Linux PM Cc: Viresh Kumar , Srinivas Pandruvada , "Zhang, Rui" , Lukasz Luba , Sudeep Holla , Morten Rasmussen , Ulf Hansson , Mario Limonciello References: From: Daniel Lezcano In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On 22/05/2023 19:12, Rafael J. Wysocki wrote: > Hi Folks, > > I'm going to submit a Power Management and Thermal Control > micro-conference proposal for LPC2023 along the lines of what happened > in the previous iterations of it. > > If you have topics that you'd like to be discussed there, please let > me know by Friday, May 26. > > Please note that LPC MC topics are expected to cover work in progress > or at the concept stage. They are not supposed to be about work that > has been done already. * Create a relevant debugfs thermal infrastructure + cleanup the sysfs debug related information. -> average temperature (overall / moving) -> mitigation episodes (duration, temperature max, min, avg, average performance througput) -> thermal zone behavior (temperature slope dT/dt vs performance througput) -> more TBD at LPC [ RFC series ready but depends on the generic trip point ] * New thermal trip types. Currently we have 'hot', 'passive', 'active', 'critical' trip points. The userspace needs to deal with the thermal also but in a different manner. Currently, it has to poll the thermal zone to get the temperature, thus introducing more wakes up on the system. However the sensors have now a programmable register to trigger an interrupt and the userspace may benefit that. By adding one or several writable 'custom' trip points, the userspace can program a point to be notified and do an action. So we separate the actions from the kernel to protect the silicon and the ones from userspace to manage the overall thermal behavior in the system at lower temperatures. [ depends on the generic trip points ] * Thermal management without the time dimension taken into account is too simplistic. Add this dimension in the thermal information for better decision (eg. notification when a temperature is above a temperature after a duration) * Improve the step wise governor. The step wise governor may take too much time to react when there are many cooling device states as it will increment with one step at each update (eg. idle cooling device has 100 states). That may result on overshoots. Depending on the temperature slope we should increase the number of steps for the cooling action. The result should be some kind of PID regulation loop but simplified regarding the power allocator. -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog