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#1 2006-10-07 10:55:19

Registered: 2006-06-05
Posts: 117

Laptop-mode tools

Have anyone really tried laptop-mode tools since there was included support for it in the kernel?

I did the other day. It's supposed to have a transparent data buffer between the harddrive and the user. So upon writing/reading any data to the disc the data won't be written until this buffer reaches some size, to prevent it from reading/writing all the time to the harddrive.

This is said to save precioius battery time from our laptops. After trying it out, I must give it a 1 / 10 grade. The harddrive does spin down a little more often (yay) but every time it spind up more energy is required that just what it would take to leave it on. So frequent use of the harddrive would probably have the opposite effect.
But that's not the reason I found quite useless. It's because of the overly noticable lag it creates every time you type 'ls'. It means you must wait for the harddrive to spin up, give it (one counts about in average half a spin, ie for a 0.5 * 7200RPM / (60) RPS, for a 7200Rates Per Minute disc) the mechanical time it takes to spin up the harddrive, locate the right track and eventually the correct block.
This is a matter of rougly ½-1 seconds of delay you will face every time you want to access your harddrive. This may not sound like a big deal, but working with the command prompt and waiting 1 second for a command to finish which should come more or less instantly is rather tiresome.

So anyway, I was just going to drop in and see what you thought of it. Possibly you haven't had the 'problems' that I have. Of course, another fact of the annoying latency issues is that I'm only having a 5400RPM disc in my laptop.


#2 2006-10-07 11:07:19

Forum Fellow
From: Melbourne, Australia
Registered: 2004-10-09
Posts: 4,927

Re: Laptop-mode tools

I find it effective and useful, but it depends entirely on how you're using your computer.

When im on battery, im far more likely to be in epiphany or OOo than doing heavy CLI work, so it's quite effective and although I do experience the lag occasionally, its certainly worth it to squeeze out more life out of my laptop's dying battery. And it works. I see a noticable bump in battery life. Another good 20 minutes or so. From what was orignially a 4 hour battery, that dropped to 1 hour, is now working at a meagre 1:30 hours.

AFAIK laptop mode includes other changes to save battery too, so take a look in the config file and see if there's anything you can tweak that can make it more useful for you -- maybe make the spindown delay longer. Don't diss it till you've given it every chance.



#3 2006-10-07 12:23:40

Registered: 2006-06-05
Posts: 117

Re: Laptop-mode tools

Well that true, there's probably some tweaking to it that I haven't tried. As far as my understanding goes though, the tools pretty much work with your harddrives and nothing else.
I have about 4 hours of battery time now. What I really must find out is if I can tweak it so that the level of annoyance stands in a acceptable ratio of battery life gained.
Little / No annoyance ~ 10 minutes.
Alot of annoyance ~ 20 minutes
The first option might seem like to small of a boost to actually bother, but then again, there might be some other tool to combine it (already using cpu scaling and so on).
The second option is what the estimated level is at now, which is not really acceptable to me.

The real question is if: ( Tweaking ) + ( Finding an acceptable annoyance level ) == ( time spent tweaking )

So I've been ranting on about this for a good five minutes now. Could've probably found a good middle alternative to this by now. Ah well, I'll add it to my todo list smile


#4 2006-10-12 07:57:15

From: Not-so-sunny Hawaii
Registered: 2006-06-13
Posts: 383

Re: Laptop-mode tools

i've messed with laptop-mode quite a bit in my quest for better battery, and it earned me a meager 15 minutes on top of my roughly 3:30.  This is after installing a CPU auto-throttler (cpudyn), which gave me a whopping hour and a half, up from 2 hours

<zyth> OH GOD IT HURTS rauble
<Monk-e> rauble, roflrofl
<Monk-e> wtf?
<rauble> arpil fooz!


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