Linux laptops, revisited (can any sleep like my PowerBook does?)

Charles Curley charlescurley at charlescurley.com
Tue Jan 22 09:09:35 MST 2008


On Mon, Jan 21, 2008 at 10:45:58PM -0700, Michael L Torrie wrote:
> Charles Curley wrote:
> > On Mon, Jan 21, 2008 at 10:44:43AM -0700, Michael L Torrie wrote:
> >> This thread has been enlightening, to say the least.  But not super
> >> encouraging.  What I'm getting from this thread is that suspend to ram
> >> is possible on some laptops.  But it may require some assembly.
> > 
> > Ubuntu 7.10 just fell into place on my Thinkpad R51
> > (http://www.charlescurley.com/Lenovo.R51.html), including
> > suspending. While I haven't tried suspending to RAM, suspending to
> > hard drive works just fine.
> 
> You've inadvertently confirmed what I am coming to fear.  That
> suspending doesn't just work.  As you experience, hibernating to disk
> works for the vast majority of users on most laptops (or even desktops).
>  Mainly because it has nothing much to do with power management.
> Suspending, in my mind, means suspend to RAM (sleep).  I would be
> interested to hear of your experiences with this.

Well, that's what you get for drawing a conclusion on insufficient
data. I was silent on suspend not because it doesn't work but because
I had not done the experiment since installing Ubuntu 7.10. In fact it
has worked in the past with various Fedora (see my writeup). For the
halibut, I just did the experiment by closing the lid. Suspend works
just fine and dandy, wireless network and all.


> 
> After using my powerbook for 4 years or more, I don't know how anyone
> lives without it, or stands for anything other than fast suspend and
> resume.

Well, I guess you don't know me. One of my concerns is battery
life. My usual MO for unplugged use is to move the laptop from point A
to B. If I suspend, I use battery power. If I hibernate, I
don't. Usually the time taken is of minor concern because I have other
things to do while the laptop is hibernating or resuming.

> Powering on and off the entire laptop (which is what hibernate
> aka suspend to disk still involves) is time consuming.  In this day and
> age we should expect/demand that our machines go to sleep very quickly
> and awake, ready for work, in the state we last left them, in just a
> second or two.  And I think I can legitimately demand this from linux on
> a thinkpad, of all machines.  I find it really odd how many of the folks
> I've talked to think hibernation is good enough.

Maybe some folks aren't in all that much of a hurry.

> 
> Works fine on AMD machines, for the most part.
> 
> > Actually it runs just fine while plugged in, which means it is good
> > preparation for running on battery. While plugged in, right now my
> > processor is running at 600 MHz 97% of the time, and 95% in C2 state,
> > whatever that means.
> 
> It runs fine, but can't give you a CPU electricity use estimate when the
>  AC is plugged in.

Ah, that makes sense.

> 
> Idling the CPU down to the lowest speed when not needed is indeed a very
> good thing.  The bigger the C number (like C4), the less power the CPU
> uses in that state, but the longer it takes the CPU to return to a state
> where it can process instructions, or something to that effect.  I read
> somewhere that on laptops, you should shoot for most of your time in the
> C3 state when you are trying to max out battery life.  See the powertop
> FAQ on this.


Well, then I must be doing something right, even if inadvertently.

> 
> It turns out that lots of common software, including firefox,
> gaim/pidgin, and even gvim can, without correct settings and even
> patches, sap your battery.  See
> http://www.lesswatts.org/projects/powertop/known.php for tips.

That makes sense. Most applications are written with desktops, not
laptops, in mind. Also see the tips & tricks section.

-- 

Charles Curley                  /"\    ASCII Ribbon Campaign
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