Date: Thu, 20 Nov 2008 22:32:57 +0100 From: martinko <gamato@users.sf.net> To: freebsd-mobile@freebsd.org Cc: freebsd-acpi@freebsd.org Subject: Re: Is the C3 possible with SMP? Message-ID: <gg4l29$po2$1@ger.gmane.org> In-Reply-To: <1225664813.1202.5.camel@RabbitsDen> References: <490DF584.5080506@FreeBSD.org> <1225656933.1202.2.camel@RabbitsDen> <490E245C.7070900@FreeBSD.org> <1225664813.1202.5.camel@RabbitsDen>
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Alexandre "Sunny" Kovalenko wrote: > On Mon, 2008-11-03 at 00:06 +0200, Alexander Motin wrote: >> Alexandre "Sunny" Kovalenko wrote: >>>> 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. >>>> >>> You can get half way there by adding >>> >>> dev.cpu.1.cx_lowest=C3 >>> >>> to /etc/sysctl.conf >> Thanks. >> >> 1. Looks like it does not kill the timer. >> 2. I haven't got any benefit from it in idle state. According to >> `acpiconf -i 0` I have about 13 Amps (IMHO more looks like Watts) with >> both C2 and this half-to-C3, but only 11 Amps in full C3 (but without >> timer). >> 3. I have got about 10% benefit (33 Amps against 36) when cpu0 is 100% >> busy while cpu1 is idle. >> > You would not happen to have USB loaded or built into kernel? If you do, > you will practically never go into C3. What does > > sysctl dev.cpu | grep cx_usage > > say? > Hi, My laptop reports C1 state only: $ sysctl -a | grep cx_ hw.acpi.cpu.cx_lowest: C1 dev.cpu.0.cx_supported: C1/1 dev.cpu.0.cx_lowest: C1 dev.cpu.0.cx_usage: 100.00% But this is Pentium-M and I remember it could use C2 and C3 back with 5.x kernel and I'm sure I had USB as I have now. Do you have any idea why I don't have C2/C3 states available anymore ?? Cheers, Martin
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