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I am really really confused about the power management tools available for Linux: I have Arch Linux with XFCE on my laptop.
The guides on the the Arch Linux wiki list
acpi
acpid
pm-utils
cpufreq
laptop-mode-tools
to manage power, suspension, disks and CPU, WiFi, etc.
But I can't understand what the relationships between them are. Apparently they don't require each other (dependencies are listed as optional) but it's not clear to me what this implies: do they work together doing different things or are they alternative to each others or conflict with each other or what?
At the moment I only have pm-utils
(+upower
) installed. Do I also need acpi
and/or acpid
? And what about laptop-mode-tools
: is this kind of supervisor of all the other tools? If so, should I configure only laptop-mode-tools
or also each of the other tools separately? How do they interact with lm-sensors
and cpufreq
?
In addition to this, there is XFCE Power Manager, which seems to be unrelated to any of the above tools, as it works even if they are not installed. So my question is again, if I install the others will they conflict with XFCE Power Manager? And what about the power management options included in Xscreensaver
? Do they conflict or do they override the settings in XFCE Power Manager (or acpi
or pm-utils
)?
All I want to do really is to have an efficient use of energy:
- be able to go to standby/suspension
- don't have the fan running all the time
- don't overheat/damage the CPU and the hard drive
- turn off WiFi when in standby/suspension
- et cetera
thanks a lot for your explanation. Let me see if I understand: Xfce Power Manager is a sort of 'GUI' which relies on upower, which needs pm-utils and also acpid (although acpid is not a dependency but this might be an archlinux issue). pm-utils does only suspend and laptop-mode-tools does other adjustments, but they do not conflict because they do different things. However they both need acpid to know what is going on. And finally cpufreq (and cpufreqd) are probably not necessary because the kernel should take care of that. Is this more or less correct? – rs028 – 2011-08-15T18:32:41.667
@rsom: XfPM is both a GUI for adjusting the settings, and also a daemon that ensures the settings are applied. Other than that, correct. – user1686 – 2011-08-15T18:37:31.833
but it does so by passing orders to the other tools (sort of a higher-level daemon)? Also what about the power management settings in Xscreensaver? do they override those in XfPM or vice versa? – rs028 – 2011-08-15T18:53:39.883
AFAIK, Xscreensaver does not do any power-management on its own - it simply sets the apropriate parameters in the X11 server. (Try
xset q
.) It could be that Xfpm simply manages the same settings, or that it doesn't manage the screen at all and lets the screensaver do it. (I'm using GNOME, which has its own program named "GNOME Screensaver", and I don't know whether Xscreensaver is Xfce's default... Reading the source of Xfpm would perhaps give the best answer.) – user1686 – 2011-08-15T20:52:12.957I think I understand a lot better now. thanks a bunch. – rs028 – 2011-08-16T14:44:37.083
Also, yes, Xfpm orders upower to change various settings or to suspend the machine. (I'm not sure, though, if it uses upower for everything or just certain parts.) – user1686 – 2011-08-16T15:25:15.397
@grawity: Your incorrect in regards to
upower
requiringacpid
. It does not requireacpid
, and from what I could understand, it never did. your simplistic explanation removed this confusion, simply install both. The reality is I installedupower
andpm-utils
, yet have all the featuresacpid
provides. The question is why? – J. M. Becker – 2012-05-01T01:32:14.663Looks like I just found my answer, I read this statement on a Debian Sid wiki page. "If you use laptop-mode-utils it depends on acpid, pm-utils has options that can replace laptop-mode-tools by placing scripts in /etc/pm/power.d/" – J. M. Becker – 2012-05-01T01:36:24.797