On 05/03/14 22:29, Adrian Chadd wrote:
On 3 May 2014 21:52, Allan Jude <free...@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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