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Date:      Sun, 02 Nov 2008 20:46:28 +0200
From:      Alexander Motin <mav@FreeBSD.org>
To:        FreeBSD acpi <freebsd-acpi@freebsd.org>, freebsd-mobile@FreeBSD.org
Subject:   Is the C3 possible with SMP?
Message-ID:  <490DF584.5080506@FreeBSD.org>

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Hi.

I have tried to enable C3 state on my Core2Duo laptop and found that it 
is not working good. System HZ timer stops during CPU sleep. After some 
investigation I have found that it is due to LAPIC timer used for HZ 
stopped during C3 state (same as during AMD's C1E).

So the question is: Is it possible (or planned) to make it work somehow? 
For example, by using some external timer instead of LAPIC's one?

ACPI reports about 20% less idle power consumption with C3 state 
comparing to C2. It would be interesting to get additional half an hour 
on battery.

-- 
Alexander Motin



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