Date: Thu, 11 Aug 2016 02:54:42 +1000 (EST) From: Ian Smith <smithi@nimnet.asn.au> To: Aleksander Alekseev <afiskon@devzen.ru> Cc: freebsd-questions@freebsd.org Subject: Re: Power consumption tuning Message-ID: <20160811015734.D79687@sola.nimnet.asn.au> In-Reply-To: <mailman.109.1470830402.42128.freebsd-questions@freebsd.org> References: <mailman.109.1470830402.42128.freebsd-questions@freebsd.org>
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In freebsd-questions Digest, Vol 636, Issue 4, Message: 2 On Tue, 9 Aug 2016 17:23:45 +0300 Aleksander Alekseev <afiskon@devzen.ru> wrote: > Hello. > > I'm exploring how power consumption could be tuned on FreeBSD 11.0. I > discovered a few useful articles, for instance [1]. Also useful pieces > of advice were given on IRC. Resulting list is for now like this: > > * Use lightweight software (i3, GTK based GUI applications, etc), turn > off unused kernel modules, don't use full disc encryption, etc You don't need to 'turn off' unused modules, just don't load what you don't need :) More a memory use than power consumption issue? > * Reduce CPU frequency (sysctl dev.cpu.0.freq), use powerd to do it > automatically Yes. Its default parameters are usually a useful starting point. > * Reduce display brightness (sudo pkg install intel-backlight) > * Enable power save mode on NIC (sudo ifconfig wlan0 powersave) Check that your particular NIC works well in powersave mode. > * Disable unused USB devices (sudo usbconfig -d X.Y power_off) This might not win much, at least my webcam device saved maybe 150mW, and it wasn't good through suspend / resume without some fiddling. > * Reduce clock frequency (kern.hz = 100) I'm not convinced this wins much, power-wise, any more. With modern event counters mechanism - here HPET, one-shot mode - and kern.hz=1000 I see no more than 65-75 clock interrupts/s when idle, 2-300/s busy .. and that's on FreeBSD 9.3. > * Make sure your kernel is built without INVARIANTS and WITNESS You haven't said if this is for a desktop or laptop machine, two very different power consumption scenarios. Mention of [1] would suggest a laptop as that's what mav@'s work was focussed on there. > Perhaps there are other methods I didn't notice? For instance are there > any other sysctl parameters or kernel configuration options worth > trying? Well [1] stresses the importance of using maximum available C-states on your hardware. But except for powerd and C-states where possible, I wouldn't bother with all that to save an extra few watts on a desktop. > [1] https://wiki.freebsd.org/TuningPowerConsumption > Best regards, > Aleksander Alekseev What hardware? What OS version? cheers, Ian
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