Messages in this thread | | | Date | Tue, 26 Apr 2022 08:41:26 +0530 | From | Viresh Kumar <> | Subject | Re: [RFC PATCH v3 0/5] Introduce Cpufreq Active Stats |
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On 06-04-22, 23:08, Lukasz Luba wrote: > Hi all, > > This is the 3rd version of patch set which tries to address issues which are > due to missing proper information about CPU performance in time. > > The issue description: > 1. "Cpufreq statistics cover the time when CPUs are in idle states, so they > are not suitable for certain purposes, like thermal control." Rafael [2] > 2. Thermal governor Intelligent Power Allocation (IPA) has to estimate power, > for the last period, e.g. 100ms, for each CPU in the Cluster, to grant new > power and set max possible frequency. Currently in some cases it gets big > error, when the frequency of CPU changed in the middle. It is due to the > fact that IPA reads the current frequency for the CPU, not aware of all > other frequencies which were actively (not in idle) used in the last 100ms. > > This code focuses on tracking the events of idle entry/exit for each CPU > and combine them with the frequency tracked statistics inside internal > statistics arrays (per-CPU). In the old cpufreq stats we have one shared > statistics array for the policy (all CPUs) and not take into account > periods when each CPU was in idle. > > Sometimes the IPA error between old estimation signal and reality is quite > big (>50%).
It would have been useful to show how the stats hierarchy looks in userspace now.
-- viresh
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