Date: Fri, 27 Oct 2006 09:08:55 -0700 From: Nate Lawson <nate@root.org> To: Ian Smith <smithi@nimnet.asn.au> Cc: acpi@freebsd.org Subject: Re: powerd: add support for limiting cpu frequency on adaptive mode Message-ID: <45422F17.4000704@root.org> In-Reply-To: <Pine.BSF.3.96.1061027175636.1051A-100000@gaia.nimnet.asn.au> References: <Pine.BSF.3.96.1061027175636.1051A-100000@gaia.nimnet.asn.au>
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Ian Smith wrote: > On Thu, 26 Oct 2006, Kevin Oberman wrote: > > > > Can someone look on the pr > > > (http://www.freebsd.org/cgi/query-pr.cgi?pr=bin/104689) I sent. Maybe > > > the patch is dirty but I think that idea is nice and with it battery > > > lives really longer. > > > > YES! When I am on battery for an extended time, I am very happy to have > > the system max out at a MUCH lower speed if I can keep basic capabilities > > for simple stuff like editing and such. Slight slow-downs are not an > > issue. > > The problem I see with this patch as it stands is that it affects both > battery and AC power adaptive modes (ie, powerd default operating mode) > > Stepan says in the PR: > > "Apply the patch and run powerd: > powerd -a maximum -b adaptive -m 558 > Where 558 is maximum frequency on adaptive mode" > > I want to run adaptive mode on 'AC' both because it uses half the power > when idle and greatly reduces the laptop's temperature (Thinkpad T23). > 'AC' in quotes, this being a 100% solar power home; every watt counts. > > Were the -m switch function ANDed with (acline_status = SRC_BATTERY) or > perhaps, allowing for SRC_UNKNOWN, (acline_status != SRC_AC) then you > could still use adaptive mode at full speed on 'AC' when required and > take advantage of setting a maximum speed while running on battery? > > > That said, power consumption is NOT intuitive. If I am playing an MP3 > > (very constant CPU load) at a speed where the CPU is at about 80%, the > > system uses more power than when the CPU is at 30%. In either case, the > > MP3 playback is fine. (This was on my T30 with a 1.8G P4M CPU, so it's > > not the best for power use.) > > The T23 is only a two-speed P3M (1133/733) so I've yet to see the full > potential of powerd, nor have I played with its idle/busy shift points > or examined hysteresis between load shift points at various freqs, but > it's already a Very Good Thing here .. > > > I know that Windows wants to reduce maximum CPU speed when running on > > battery, so I do believe this is a good thing. > > If limited to while running on battery only, I'd heartily agree. > Meanwhile of course you can run powerd -b min though that might be > overkill if you have lots of freqs available .. I'll say it again: we need real profiles, not more command line flags. The first person to add a .y and define a config file format gets a cookie. I just haven't found anyone willing to put in that design effort. -- Nate
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