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Date:      Sat, 10 Jan 2009 01:55:29 +0200
From:      Alexander Motin <mav@FreeBSD.org>
To:        Gabriel Lavoie <glavoie@gmail.com>
Cc:        freebsd-acpi@freebsd.org
Subject:   Re: EST (Enhanced Intel SpeedStep(R) Technology) on amd64
Message-ID:  <4967E3F1.3050002@FreeBSD.org>
In-Reply-To: <1231543382.00058245.1231531801@10.7.7.3>
References:  <1231471393.00057821.1231461001@10.7.7.3> <1231492987.00057896.1231480801@10.7.7.3> <1231514587.00058037.1231502401@10.7.7.3> <1231532583.00058199.1231520401@10.7.7.3> <1231543382.00058245.1231531801@10.7.7.3>

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Gabriel Lavoie wrote:
> Another question. Any reason why powerd doesn't use
> dev.est.0.freq_settings when it is available instead of
> dev.cpu.0.freq_levels?
> 
> On my system:
> dev.cpu.0.freq_levels: 2500/88000 2187/77000 2000/47608 1750/41657
> 1600/44616 1400/39039 1200/41800 1050/36575 900/31350 750/26125
> 600/20900 450/15675 300/10450 150/5225
> dev.est.0.freq_settings: 2500/88000 2000/47608 1600/44616 1200/41800

dev.cpu.0.freq_levels is just a mix of est and p4tcc levels. By default 
powerd uses all of them. If you really wish, you can disable p4tcc with:
hint.p4tcc.0.disabled=1
hint.acpi_throttle.0.disabled=1
then dev.cpu.0.freq_levels will be equal to dev.est.0.freq_settings.

> If I don't lower the polling time of powerd to 100ms, my system
> becomes way too much unresponsive because powerd takes too much time
> to increase the frequency, step by step and there are a lot of
> settings with dev.est.0.freq_settings (14). With
> dev.est.0.freq_settings, the minimal setting is high enough so the
> system stays responsive and powerd would bring it up to max frequency
> quickly enough, even if the polling time is still kept at 500ms. This
> would work more like Windows or Linux where the lowest frequency at
> which the CPU will drop is the lowest EIST gives (here 1200 MHz).

I have just merged updated powerd to 7-STABLE to address this issue.

-- 
Alexander Motin



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