Date: Sun, 02 May 2004 15:01:15 -0700 From: "Kevin Oberman" <oberman@es.net> To: Peter Schuller <peter.schuller@infidyne.com> Cc: freebsd-mobile@freebsd.org Subject: Re: Laptop ACPI question Message-ID: <20040502220115.BBA985D0A@ptavv.es.net> In-Reply-To: Your message of "Sun, 02 May 2004 23:41:47 %2B0200." <200405022341.47310.peter.schuller@infidyne.com>
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> From: Peter Schuller <peter.schuller@infidyne.com> > Date: Sun, 2 May 2004 23:41:47 +0200 > > > Actually, ACPI will greatly improve battery life soon, but not yet. The > > bits and pieces are being fed into CURRENT and I suspect that SpeedStep > > support will be coming soon. > > Cool! I always wondered what was "missing", since I get about 50% longer > battery life in Windows than in FreeBSD on my laptop (T40p). > > I read somewhere that someone mentioned something about PCI power save > modes... would this be part of SpeedStep? Will SpeedStep support bring power > consumption to the levels one gets in Windows, or is there additional power > saving features on modern laptops that need to be supported? > > (I'm asking even though it's not relevant to the original question, since you > seem to know a lot about this stuff, and I haven't found much on this > googling around.) I am learning, but I am WAY behind the experts. I just have more time to answer questions. Hopefully the answers are sometimes correct. ;-) PCI power modes are not SpeedStep but are important in power management. They are related to ACPI, but not really a part of it, as I read the spec. They are a part of the PCI spec and ACPI needs to provide control information for these for proper PCI power control. This is very important for things like suspend and resume. SpeedStep, as I understand it, is adjustment of the CPU clock speed and is VERY directly tied to battery life. It is what systems supporting SpeedStep adjust when moving from AC to battery modes. E.g. my T30, by default, runs at 1.8 GHz on AC and 1.2 GHz on battery (with my BIOS configuration). SpeedStep is a marketing name and I am unwilling to say that it is limited to the CPU speed. It may include some of the other power management tools like deep sleep modes. Support of CPU frequency is something that is actively being developed and will almost certainly be in 5.3. PCI power mode support is also in active development and was committed to CURRENT a few weeks ago, but at least partly backed out due to problems on a few laptops. (It worked GREAT on mine, though). I hope it is returned soon as it make my sound work after a suspend. The other item of importance to laptop users is turning off (not just blanking) the display. It appears that this is on the verge of commitment. I ran an early version of it and I could turn off the display on suspend for the first time without the old APM stuff. So power management is getting closer all the time and I am pretty confident (for someone who is NOT writing the code) that it will all be ready when V5 is declared STABLE. -- 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
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