Date: Mon, 25 May 2026 07:42:57 -0700 From: Chris Torek <chris.torek@gmail.com> To: Warner Losh <imp@bsdimp.com> Cc: Olivier Certner <olce@freebsd.org>, Adrian Chadd <adrian@freebsd.org>, freebsd-current <freebsd-current@freebsd.org>, ShengYi Hung <aokblast@freebsd.org> Subject: Re: AMD, CPPC, etc Message-ID: <CAPx1GvdM3yUK9vpTLYwE4yXm7R0Vzea96xAsPPrNZmEHqeb8-Q@mail.gmail.com> In-Reply-To: <CANCZdfoyqdEr_1%2Bkmi5_0TTG0VaAZMjXgGOubWt5nVK8aqe9DQ@mail.gmail.com> References: <CAPx1GvfaDdmj0vkzzinyhGm2mQRKgmOh3fpNXo-cgznoujVY-Q@mail.gmail.com> <CAJ-Vmont9jS-VqKj%2B02DCDP_Eb=UdWqPGWKrBpTn74_WfXHFjA@mail.gmail.com> <1978836.vR5SVPPSqJ@ravel> <CANCZdfoyqdEr_1%2Bkmi5_0TTG0VaAZMjXgGOubWt5nVK8aqe9DQ@mail.gmail.com>
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On my desktop system, using 0 ("auto") mode works quite well: the
system idles around 80 to 95 watts, and when building ports or
/usr/src with all 32 CPUs going, gets up to the 320-watt range, all
without any OS work required. I'm not sure what actually chooses the
CPU frequency here.
Experimentally, setting "desired performance" lower than somewhere in
the 50 to 100 range makes everything even slower than at idle (but
doesn't reduce power draw much).
This is also useful to prevent my office (at home) from overheating
(it gets very toasty during big bulids, as a couple of gcc builds +
rust etc takes several hours).
Chris
On Mon, May 25, 2026 at 6:03 AM Warner Losh <imp@bsdimp.com> wrote:
> At work, we run powerd on all our video streaming servers to save power by ramping the cpu frequency up in times of high demand, and then back down for low demand times.... it saves a lot of power. But to interpret our performance data, we have to record the settings since 90% cpu at 800MHz is way different than 90% at 3GHz... whatever we do here has to be observeable.
>
> Warner
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