Date: Fri, 27 Oct 2006 09:35:48 -0700 From: Sam Leffler <sam@errno.com> To: Nate Lawson <nate@root.org> Cc: acpi@freebsd.org Subject: Re: powerd: add support for limiting cpu frequency on adaptive mode Message-ID: <45423564.8030703@errno.com> In-Reply-To: <45422F17.4000704@root.org> References: <Pine.BSF.3.96.1061027175636.1051A-100000@gaia.nimnet.asn.au> <45422F17.4000704@root.org>
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Nate Lawson wrote: > 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. > Config files are great but I think something more dynamic is needed. In particular I'd like to see devd launch tools that inform powerd it should switch operating mode from AC -> battery. Otherwise powerd needs this builtin and then we'll have no good place to centralize power-related work (e.g. like setting wireless cards into power save mode when operating in sta mode and on battery). Or perhaps I'm not clueful here... Sam
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