Date: Sun, 08 Jun 2008 22:13:43 -0700 From: "Kevin Oberman" <oberman@es.net> To: Jeremy Chadwick <koitsu@FreeBSD.org> Cc: Evren Yurtesen <yurtesen@ispro.net>, freebsd-stable@freebsd.org, John Baldwin <jhb@freebsd.org>, Andrew Snow <andrew@modulus.org> Subject: Re: cpufreq broken on core2duo Message-ID: <20080609051343.CFD4D45010@ptavv.es.net> In-Reply-To: Your message of "Sat, 07 Jun 2008 09:48:12 PDT." <20080607164812.GA11072@eos.sc1.parodius.com>
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--==_Exmh_1212988423_87733P Content-Type: text/plain; charset=us-ascii Content-Disposition: inline > Date: Sat, 7 Jun 2008 09:48:12 -0700 > From: Jeremy Chadwick <koitsu@FreeBSD.org> > Sender: owner-freebsd-stable@freebsd.org > > On Sat, Jun 07, 2008 at 05:51:38PM +0300, Evren Yurtesen wrote: > > By the way, there is another thing I am wondering about. If I enable HTT > > and Intel Enhanced SpeedStep in bios on a 3.00GHZ p4 CPU I see: > > > > cpu0: <ACPI CPU> on acpi0 > > acpi_perf0: <ACPI CPU Frequency Control> on cpu0 > > p4tcc0: <CPU Frequency Thermal Control> on cpu0 > > cpu1: <ACPI CPU> on acpi0 > > est1: <Enhanced SpeedStep Frequency Control> on cpu1 > > est: CPU supports Enhanced Speedstep, but is not recognized. > > est: cpu_vendor GenuineIntel, msr f2700000f27 > > device_attach: est1 attach returned 6 > > p4tcc1: <CPU Frequency Thermal Control> on cpu1 > > > > dev.cpu.0.freq_levels: 1500/27000 1312/23625 1200/13000 1050/11375 900/9750 > > 750/8125 600/6500 450/4875 300/3250 150/1625 > > dev.acpi_perf.0.freq_settings: 1500/27000 1200/13000 > > dev.cpufreq.0.%driver: cpufreq > > dev.cpufreq.0.%parent: cpu0 > > dev.cpufreq.1.%driver: cpufreq > > dev.cpufreq.1.%parent: cpu1 > > dev.p4tcc.0.freq_settings: 10000/-1 8750/-1 7500/-1 6250/-1 5000/-1 3750/-1 > > 2500/-1 1250/-1 > > dev.p4tcc.1.freq_settings: 10000/-1 8750/-1 7500/-1 6250/-1 5000/-1 3750/-1 > > 2500/-1 1250/-1 > > > > and it does not allow me to set the freq. of the cpu. > > How are you setting the frequency? Are you using powerd? You do not > have to enable SpeedStep in your BIOS to achieve throttling CPU clock > speed. In fact, I would highly recommend leaving EIST/SpeedStep in the > BIOS *disabled*, and let powerd adjust the clock frequency via ACPI. I must strongly recommend against this. EST is MUCH more efficient on its control of power use than simple throttling. So much so that on my systems that support EST, I remove cpufreq from the kernel. (In all cases, throttling means either simple throttling or throttling by using TCC.) I did quite a bit of testing on power management a year or so ago and found that throttling was of value only for controlling CPU temperature. For real power management, EST works far better as it adjust frequency (actual clock rate) and CPU voltage while throttling just stops and starts the clock without changing its actual frequency. (This came as a surprise to me about 5 years ago when I first discovered it.) At idle, throttling does exactly nothing. EST reduces voltage on the CPU and saves power even when idle. At full CPU load, throttling reduces performance and power consumption equally. EST beats it by a slim margin. The big win is at moderate load. Throttling can result is very poor results for aps like video and music which will place a continuous load on the system, but only 20-60% (in the case of my test system). It tended to make the system seem sluggish. EST does a much better job in this case as it lowers CP voltage and clock rate to maximize performance while minimizing power. If your only concern is keeping the system cool, throttling will do the job, but if you want efficient power utilization, use EST if possible. -- R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: oberman@es.net Phone: +1 510 486-8634 Key fingerprint:059B 2DDF 031C 9BA3 14A4 EADA 927D EBB3 987B 3751 --==_Exmh_1212988423_87733P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (FreeBSD) Comment: Exmh version 2.5 06/03/2002 iD8DBQFITLwHkn3rs5h7N1ERApXwAJ4se7iwJndrmqZIen+JOb1ckcTcSgCglZck war9A/b4cFQcgxmSvhvw2Sg= =65cM -----END PGP SIGNATURE----- --==_Exmh_1212988423_87733P--
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