Hi,
On 10/01/2011 05:07 PM, Martin Langhoff wrote:
> On Sat, Oct 1, 2011 at 7:02 AM, Hans de Goede<hdegoede@xxxxxxxxxx> wrote:
>> The subject more or less says it all. When I startup my desktop machine (which thus
>> is always on AC), and leave it at the gdm screen it will suspend after being left
>> alone for 30 minutes. This is not good, since I only leave it powered on when I
>> intend to access it remotely.
>
> If it supports LAN-triggered wakeups, I don't see why it should be fully on :-)
>
> Not sure if Fedora 16 has the infra, but in my OLPC-tinted-glasses
> view, power mgmt / NM should allow you to say "wake-on-LAN on this
> interface", then set the WOL bits when it's going down.
>
> (Note! The WOL bits need to be frobbed every time the system goes to
> sleep. They get cleared on wakeup.)
It would then also need to identify the NIC as a stay awake source, and
only suspend after 30 minutes of no network activity.
Imagine I'm running a screen session with my irc client in there on my Fedora box,
and 30 minutes after the last resume it suspends while I'm midway typing a sentence,
then it wakes up again because of the network activity. Power management win 0, likely
even a loss (disks spinning up which may have stayed spun down otherwise, etc. User
experience suck, since I all of a sudden get a multiple seconds latency while typing.
>> I would like to suggest to change the default power policy to never suspend
>> while on AC power
>
> Thanks for helping keep the Earth warm! :-/
Well there are 2 use cases to consider here:
1) The machine has a desktop function -> just turn it off when it is not used
My desktop rarely gets an uptime > 4 hours since I even turn it off when I
go to lunch, and it has a master/slave powerstrip to also power down the
printer, display, speaker, etc. One could even argue that suspending here
will lure people in to the false sense that it is ok to leave it on since
it will go into low power mode anyways, while in reality it is still using
a significant amount of power. I'm pretty sure that if we were to bet and
measure the poweruse of my desktop once for a week using my power regime,
and once more using an always on, but suspend after 30 minutes of idle
power regime, that my power regime is significantly more efficient.
2) The machine has a server function. In this case working wake on lan and
stay active on lan are a must have and until we have those it should not
auto suspend. Once we do then it becomes a question of the latency increase
caused by this is acceptable by the use case.
>> suspending desktop
>> machines by default seems like a bad idea.
>
> That's such a 90's thinking :-)
>
> At this stage, and looking forward, suspending on idle is a good idea
> on /servers/, where you save power at the server and at the AC.
>
> There is work to do across the stack to make S/R work smoothly and
> transparently. OLPC is doing much of it -- help us getting it into
> mainstream code (and thinking!).
I for one would argue that system suspend itself is 90's thinking,
and that we should get better at dynamic powermanagement with things
like powergating and dynamic clockspeed support becoming pretty common
in all hardware one could argue that system suspend is the powersaving
answer of the 90's and that of the 2010's is becoming better at dynamic
pm. I think that a system with its disks spun down, cpu clocked down and
in its lowest powerstate, unused usb controllers in suspend, display engine
in its lowest powerstate and display pipes + connectors turned off, etc.
will come pretty close to a fully suspended system. The last big power
eater is RAM and that will be active in both scenarios.
>
> Or join the greenpeace in teaching polar bears about the wonders of
> tropical climates...
<sigh> I was already afraid people would come up with this totally uncalled
for global warming arguments </sigh> You're barking up the wrong tree here,
as described above I'm pretty aggressive about powermanagement for my desktop
machine, and I don't even have a server at home.
But sometimes I work a couple of hours from the laptop in the living room and
I need access to my desktop, so then the desktop is on (with the display turned
off, really off) untill now this worked fine, with F-16 it no longer works fine.
We've a name for that it is called a regression and it needs to be fixed.
At a minimum there should be an easy way to configure the powermanagement policy
under gdm which there currently is not. Things like Network-Manager and the
Region and Language setting already allow configuring gdm / system wide settings
from there gnome-3 user session control panel, if we want to do powermanagement
from gdm we need the same for gdm.
Regards,
Hans
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