Date: Sun, 04 May 2014 08:32:01 -0700 From: Nathan Whitehorn <nwhitehorn@freebsd.org> To: Adrian Chadd <adrian@freebsd.org>, Allan Jude <freebsd@allanjude.com> Cc: freebsd-current <freebsd-current@freebsd.org> Subject: Re: Leaving the Desktop Market Message-ID: <53665D71.6060708@freebsd.org> In-Reply-To: <CAJ-VmomjgHo-BjRd1G17CwA72By1eOLYsZFKGHRYLSLiNvZFfg@mail.gmail.com> References: <CAF6rxgkeBozvfV-L0%2BrFZ6fWRn0=Gi3BNq1kPL=-HTq0TD6MkQ@mail.gmail.com> <A70900DF-4BAA-427F-8731-01211FFD1887@mail.turbofuzz.com> <3F7430D7-3C0F-43E1-8EBD-8AA4F701497C@FreeBSD.org> <20140503155745.GA2457@La-Habana> <CAJ-VmokHQvb2S-1c08J3RECUMosQ%2Bcd1gdB91LAb5famfKqP5w@mail.gmail.com> <20140503192305.GA1847@La-Habana> <CAJ-Vmon1ZYX18SN1f=z9N=hSgpZrAxXMxiJBUDWk6LYvMRiHmw@mail.gmail.com> <CAN6yY1uo08PDsYJ2KQNjw4hYuNsNJUvRu1b0cG%2B387F6Owkukg@mail.gmail.com> <536592D1.7080403@freebsd.org> <CAN6yY1tdsitXmGeu87OBw6RZ_s0qDvuoYXbTJVjnr74k6oM4Ag@mail.gmail.com> <CAJ-Vmo=zXyuyARapz4UCaTwMtWtW_8ys0pgssHOOUhnA-5Bt4g@mail.gmail.com> <5365C78E.6030600@allanjude.com> <CAJ-VmomjgHo-BjRd1G17CwA72By1eOLYsZFKGHRYLSLiNvZFfg@mail.gmail.com>
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On 05/03/14 22:29, Adrian Chadd wrote: > On 3 May 2014 21:52, Allan Jude <freebsd@allanjude.com> wrote: > >>> * use cpufreq with some heuristics (like say, only step down to 2/3rd >>> the frequency if idle) - and document why that decision is made (eg on >>> CPU X, measuring Y at idle, power consumption was minimal at >>> frequency=Z.); >>> * make sure the lower frequencies and tcc kick in if a thermal cutoff >>> is reached; >>> * default to using lower Cx states out of the box if they're decided >>> to not be buggy. There are a few CPUs for which lower C states cause >>> problems but modernish hardware (say, nehalem and later) should be >>> fine. >> According to the wiki, in 9.x and onward there is code that is supposed >> to detect if the higher Cx states are usable, and not use them if they >> are not, but I do not know how well this works. > I'm not sure. I think those who care / know enough just put relevant > bits into /etc/rc.conf and /boot/loader.conf rather than flipping it > on by default. > > I'm kind of tempted to just flip on Cmax by default and teach powerd > to not do cpufreq unless there's a thermal issue. Then take a step > back and see what happens. > Please remember that powerd is not x86-only. Other systems (e.g. PowerPC) use it in conjunction with cpufreq. But seriously, let's just pull tcc from GENERIC. I'll do it next week unless I hear any objections. -Nathan
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