From mboxrd@z Thu Jan 1 00:00:00 1970 From: skannan@codeaurora.org Subject: Re: [PATCH] PM / devfreq: Generic cpufreq governor Date: Mon, 30 Jul 2018 11:58:36 -0700 Message-ID: <534629d03437bc8e72a62d89e726dbe5@codeaurora.org> References: <1532750217-8886-1-git-send-email-skannan@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: "Rafael J. Wysocki" Cc: MyungJoo Ham , Kyungmin Park , Chanwoo Choi , Rob Herring , Mark Rutland , Linux PM , devicetree@vger.kernel.org, Linux Kernel Mailing List , rjwysocki@gmail.com List-Id: linux-pm@vger.kernel.org On 2018-07-29 03:52, Rafael J. Wysocki wrote: > On Sat, Jul 28, 2018 at 5:56 AM, Saravana Kannan > wrote: >> Many CPU architectures have caches that can scale independent of the >> CPUs. >> Frequency scaling of the caches is necessary to make sure the cache is >> not >> a performance bottleneck that leads to poor performance and power. The >> same >> idea applies for RAM/DDR. >> >> To achieve this, this patch adds a generic devfreq governor that can >> listen >> to the frequency transitions of each CPU frequency domain and then >> adjusts >> the frequency of the cache (or any devfreq device) based on the >> frequency >> of the CPUs. >> >> To decide the frequency of the device, the governor does one of the >> following: >> >> * Uses a CPU frequency to device frequency mapping table >> - Either one mapping table used for all CPU freq policies (typically >> used >> for system with homogeneous cores/clusters that have the same >> OPPs. >> - One mapping table per CPU freq policy (typically used for ASMP >> systems >> with heterogeneous CPUs with different OPPs) >> >> OR >> >> * Scales the device frequency in proportion to the CPU frequency. So, >> if >> the CPUs are running at their max frequency, the device runs at its >> max >> frequency. If the CPUs are running at their min frequency, the >> device >> runs at its min frequency. And interpolated for frequencies in >> between. > > While not having looked at the details of the patch yet, I would > change the name of the feature to "Generic cpufreq transition > governor" to make it somewhat less ambiguous. In my opinion it makes it look MORE like this is a cpufreq governor. How about the following? PM / devfreq: Generic cpufreq to devfreq mapping governor Seem a lot more clear to me. I'm open to suggestions for the devfreq governor name too. "cpufreq" has been very confusing so far. cpufreq-map maybe? Thanks, Saravana