Date: Sun, 4 May 2014 21:27:21 -0700 From: Kevin Oberman <rkoberman@gmail.com> To: Nathan Whitehorn <nwhitehorn@freebsd.org> Cc: FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: Leaving the Desktop Market Message-ID: <CAN6yY1upJr4wcEfZhKCE%2BSCcWs=rBJvzaWWz98VSCA9AkMEPyw@mail.gmail.com> In-Reply-To: <536673ED.207@freebsd.org> 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> <20140504142839.GA9271@La-Habana> <53666102.5080205@allanjude.com> <53667352.4030807@allanjude.com> <536673ED.207@freebsd.org>
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On Sun, May 4, 2014 at 10:07 AM, Nathan Whitehorn <nwhitehorn@freebsd.org>w= rote: > On 05/04/14 10:05, Allan Jude wrote: > >> On 2014-05-04 11:47, Allan Jude wrote: >> >>> On 2014-05-04 10:28, Matthias Apitz wrote: >>> >>>> El d=C3=ADa Saturday, May 03, 2014 a las 04:59:48PM -0700, Kevin Oberm= an >>>> escribi=C3=B3: >>>> >>>> On Sat, May 3, 2014 at 1:25 PM, Adrian Chadd <adrian@freebsd.org> >>>>> wrote: >>>>> >>>>> Set it to the lowest available Cx state that you see in dev.cpu.0 . >>>>>> >>>>>> >>>>>> Available is not required. Set it to C8. That guarantees that you >>>>> will use >>>>> the lowest available. The correct incantation in rc.conf is "Cmax". >>>>> performance_cx_lowest=3D"Cmax" >>>>> economy_cx_lowest=3D"Cmax" >>>>> >>>>> But, unless you want laggy performance, you will probably also want: >>>>> hint.p4tcc.0.disabled=3D1 >>>>> hint.acpi_throttle.0.disabled=3D1 >>>>> in /boot/loader.conf. Low Cx states and TCC/throttling simply don't m= ix >>>>> well and TCC is not effective, as mentioned earlier in this thread. >>>>> >>>> Re/ powerd I have in /etc/rc.conf: >>>> >>>> # powerd >>>> powerd_enable=3D"YES" >>>> powerd_flags=3D"-a max -b adp" >>>> # >>>> performance_cx_lowest=3D"Cmax" >>>> economy_cx_lowest=3D"Cmax" >>>> >>>> (and the additional hint.* in /boot/loader.conf as well). Which proces= s >>>> 'performance_cx_lowest' and 'economy_cx_lowest' target exactly as conf= ig >>>> values? >>>> >>>> Thx >>>> >>>> matthias >>>> >>>> In a pretty unscientific test on my laptop (Lenovo T530 with Intel i5 >>> 3320M), setting hw.acpi.cpu.cx_lowest=3DC8 lowered power consumption at >>> idle by about 3 watts, which adds about 30-45 minutes to my battery lif= e >>> during conservative usage. >>> >>> Using PCBSD 10, so hint.acpi_throttle.0.disabled=3D1 was already set >>> (apparently solves some issue with powerd on some AMD systems) >>> >>> I have added hint.p4tcc.0.disabled=3D1 but not sure where to expect to = see >>> a difference. >>> >>> I see the difference now, with the p4tcc stuff disabled, the lowest >> cpufreq is now 1200mhz instead of 150mhz >> >> >> > I just set the default for acpi_throttle and p4tcc in HEAD to disabled by > adding these line to the default /boot/device.hints. If you want them bac= k, > editing your device.hints will restore them. This can be reverted if many > people want throttling enabled by default, but all I have heard so far -- > and for the past many years -- is a unanimous chorus to turn it off. > -Nathan > Anyone playing around with Thermal Management should read the article on Tom's Hardware on the subject. It explains things quite nicely. Even I could understand it. :-) http://www.tomshardware.com/reviews/cpu-cooler-fails,1695-3.html The section on Thermal Monitor 2 was new to me as it has been added since I last researched this several years ago. Note the tie-in between TM2 and EST rather than simple throttling (skipping N of every 8 clock cycles). Section 2 of the article has thermal specs on a lot of processors, too.. Bottom line of the article is to make sure TM2 is enabled and just leave it alone to do its thing. No throttling of any sort for power mis-management. The one area that can stand a close look is the algorithm for adjusting EST. It probably will make far less difference than C-states, but it is a legitimate power management technique and it is under the control of powerd. Several people have suggested modification for this and I think it's at least worth a look. Finally, if we don't default p4tcc and throttling to off and change the default for C-states to Cmax, a lot of people will be very unhappy. Disabling throttling really must come first. --=20 R. Kevin Oberman, Network Engineer, Retired E-mail: rkoberman@gmail.co <rkoberman@gmail.com>
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