Date: Thu, 25 Mar 2010 10:10:03 GMT From: Dan Lukes <dan@obluda.cz> To: freebsd-acpi@FreeBSD.org Subject: Re: kern/144232: [cpufreq] [patch] Add debug.cpufreq.highest to cpufreq Message-ID: <201003251010.o2PAA35L086683@freefall.freebsd.org>
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The following reply was made to PR kern/144232; it has been noted by GNATS. From: Dan Lukes <dan@obluda.cz> To: bug-followup@FreeBSD.org, spawk@acm.poly.edu Cc: Subject: Re: kern/144232: [cpufreq] [patch] Add debug.cpufreq.highest to cpufreq Date: Thu, 25 Mar 2010 11:04:15 +0100 It sound like improper place for implementation of such logic. Cpufreq is hardware driver - it allow others to control CPU speeds. It do no own decisions nor should do (imho). When it should not do decisions, then it's not appropriate place to store variables that exist for the purpose of such decision process only. cpufreq consumers (like powerd or acpi_thermal) are there for decision making so such logic and configuration variables should be there. The debug.cpufreq.lowest is here because some reported levels are not usable in the real, not because someone decided he don't want to use it. You may be interested that requested feature is implemented as part of acpi_thermal. From man acpi_thermal: hw.acpi.thermal.tz%d.passive_cooling If set to 1, passive cooling is enabled. It does cooling without fans using cpufreq(4) as the mechanism for controlling CPU speed. Default is enabled for tz0 where it is available. It require support from ACPI on your notebook which may or may not be present. If such support is not present, so acpi_thermal can't help you, then another "frequency decision" utility - e.g. - powerd - is candidate-place to implement requested logic. No logic should belong to cpufreq device driver itself, so no tunables for them there. I noticed the argument "maximum on AC is another than maximum on battery", but power state is available to powerd, so the logic we are speaking about can count the power state as well. The only question is - how to tell to powerd what we want from it exactly. Dan
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