Messages in this thread | | | Subject | Re: [PATCH v2 02/10] cpufreq: provide data for frequency-invariant load-tracking support | From | Dietmar Eggemann <> | Date | Tue, 11 Jul 2017 16:21:06 +0100 |
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On 11/07/17 07:39, Viresh Kumar wrote: > On 10-07-17, 14:46, Rafael J. Wysocki wrote: >> This particular change is about a new feature, so making it in the core is OK >> in two cases IMO: (a) when you actively want everyone to be affected by it and > > IMO this change should be done for the whole ARM architecture. And if some > regression happens due to this, then we come back and solve it. > >> (b) when the effect of it on the old systems should not be noticeable. > > I am not sure about the effects of this on performance really. > > @Dietmar: Any inputs for that ?
Like I said in the other email, since for (future) arm/arm64 fast-switch driver, the return value of cpufreq_driver->fast_switch() does not give us the information that the frequency value did actually change, we have to implement arch_set_freq_scale() in the driver. This means that we probably only implement this in the subset of drivers which will be used in platforms on which we want to have frequency-invariant load-tracking.
A future aperf/mperf like counter FIE solution can give us arch-wide support when those counters are available.
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