From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 51AE1E3; Tue, 12 Dec 2023 10:51:44 -0800 (PST) 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 69D191FB; Tue, 12 Dec 2023 10:52:30 -0800 (PST) Received: from [192.168.178.6] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id AF61D3F762; Tue, 12 Dec 2023 10:51:41 -0800 (PST) Message-ID: Date: Tue, 12 Dec 2023 19:51:41 +0100 Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 23/23] Documentation: EM: Update with runtime modification design Content-Language: en-US To: Lukasz Luba , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, rafael@kernel.org Cc: rui.zhang@intel.com, amit.kucheria@verdurent.com, amit.kachhap@gmail.com, daniel.lezcano@linaro.org, viresh.kumar@linaro.org, len.brown@intel.com, pavel@ucw.cz, mhiramat@kernel.org, qyousef@layalina.io, wvw@google.com References: <20231129110853.94344-1-lukasz.luba@arm.com> <20231129110853.94344-24-lukasz.luba@arm.com> From: Dietmar Eggemann In-Reply-To: <20231129110853.94344-24-lukasz.luba@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 29/11/2023 12:08, Lukasz Luba wrote: > Add a new section 'Design' which covers the information about Energy > Model. It contains the design decisions, describes models and how they > reflect the reality. Remove description of the default EM. Change the > other section IDs. Add documentation bit for the new feature which > allows to modify the EM in runtime. > > Signed-off-by: Lukasz Luba > --- > Documentation/power/energy-model.rst | 206 +++++++++++++++++++++++++-- > 1 file changed, 196 insertions(+), 10 deletions(-) > > diff --git a/Documentation/power/energy-model.rst b/Documentation/power/energy-model.rst > index 13225965c9a4..1f8cf36914b1 100644 > --- a/Documentation/power/energy-model.rst > +++ b/Documentation/power/energy-model.rst > @@ -72,16 +72,48 @@ required to have the same micro-architecture. CPUs in different performance > domains can have different micro-architectures. > > > -2. Core APIs > +2. Design > +----------------- > + > +2.1 Runtime modifiable EM > +^^^^^^^^^^^^^^^^^^^^^^^^^ The issue I see here is that since now the EM is runtime modifiable and there is only one EM people might be confused in locking for a non-runtime modifiable EM. (which matches the design till v4). So 'runtime modifiability' is now feature of the EM itself. There is also a figure in this document illustrating the use of em_get_energy(), em_cpu_get() and em_dev_register_perf_domain(). I wonder if this should be extended to cover all the new interfaces created for the 'runtime modifiability' feature? [...]