Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Sun, 29 Jul 2018 12:52:02 +0200 | Subject | Re: [PATCH] PM / devfreq: Generic cpufreq governor |
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On Sat, Jul 28, 2018 at 5:56 AM, Saravana Kannan <skannan@codeaurora.org> 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.
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