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Mon, 25 May 2026 07:43:09 -0700 (PDT) List-Id: Discussions about the use of FreeBSD-current List-Archive: https://lists.freebsd.org/archives/freebsd-current List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-current@FreeBSD.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 References: <1978836.vR5SVPPSqJ@ravel> In-Reply-To: From: Chris Torek Date: Mon, 25 May 2026 07:42:57 -0700 X-Gm-Features: AVHnY4K6DyeTukcRFer4Ttwxvh89BLDbdWwLW5Vvh2fZRLw5NqIZYpEoIVfH67Q Message-ID: Subject: Re: AMD, CPPC, etc To: Warner Losh Cc: Olivier Certner , Adrian Chadd , freebsd-current , ShengYi Hung Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[]; TAGGED_FROM(0.00)[]; ASN(0.00)[asn:15169, ipnet:2a00:1450::/32, country:US] X-Rspamd-Queue-Id: 4gPJXN1cQ1z3g5l X-Spamd-Bar: ---- X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated 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=E2=80=AFAM Warner Losh wrote: > At work, we run powerd on all our video streaming servers to save power b= y 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 perf= ormance 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