If you don't need infrared support, disable it in the
BIOS or shutdown the IrDA® device driver. There are also some
IrDA® features of the kernel
which are useful for saving power.
PCMCIA services consume much power, so shut them down if you don't need them.
I'm not sure to which extend the backlight consumes power.
As far as I know this device can only bear a limited
number of uptime circles. So avoid using screensavers,
which turn off the backlight.
If you want do it anyhow, you may use xset +dpms
and xset dpms 0 0 300 This turns the screen off
after 5 minutes of inactivity. Works only if the display is DPMS
For some examples to build batteries with increased uptime up to
8 hours look at
For information about APM look at the chapter
The "noatime" option when mouting filesystems tells the kernel to
not update the access time
information of the file. This information, although sometimes useful, is
not used by most people. Therefore, you can safely disable it, then
preventing disk access each time you cat a file. Here
is an example of a
/etc/fstab with this
power-saving option: /dev/hda7 /var ext2 defaults,noatime 0 2
hdparm is a Linux disk utility that lets you
set spin-down timeouts and other disk parameters.
Mobile Update Daemon
This is a drop-in replacement for the standard update
daemon, mobile-update minimizes disk spin ups and
reduces disk uptime. It flushes buffers only when other disk activity is
present. To ensure a consistent file system call sync
manually. Otherwise files may be lost on power failure.
mobile-update does not use APM. So it works also on
: noflushd monitors disk activity and spins down
disks that have been idle for more than <timeout> seconds. It
requires a kernel >=2.2.11 . Useful in combination with
hdparm and mount with
noatime option to bring down disk activity.
Here are some comments and thoughts by Nat Makarevitch
about a possible approach which may
reduce the disk activity under Linux (sparing energy, especially with
noflushd) the file Documentation/filesystems/proc.txt of the Linux sourcetree
documents some useful features, esp. in the
Under Linux 2.2 I used:
echo "100 5000 8 256 500 60000 60000 1884 2" > /proc/sys/vm/bdflush
especially under Linux 2.4 which uses its spare time to 'pre-save' the
less-used memory pages into the swap, increasing the disk activity
I tried to figure the more adequate parameters (Linux 2.4.9, 192 MB RAM,
Toshiba 3480 laptop)
beware: some of those parameters may be dangerous or useless (I have not
gathered serious data about the practical efficiency). moreover do not
forget that delaying disk writes of data is intrinsically dangerous
echo 99 512 32 512 0 300000 60 0 0 > /proc/sys/vm/bdflush
# is '60' the max value for age_super?
echo 1 1 96 > /proc/sys/vm/buffermem
echo 512 128 32 > /proc/sys/vm/kswapd
echo 1 10 96 > /proc/sys/vm/pagecache
Toshiba Linux Utilities
are a set of Linux utilities for controlling the fan, supervisor passwords,
and hot key functions of Toshiba Pentium notebooks.
There is a KDE package Klibreta, too.
At Kenneth E. Harker's page there is a recommendation for LCDproc
. "LCDproc is a small piece of software that will enable your Linux
box to display live system information on a 20x4 line backlit
LCD display. This program shows, among other
things, battery status on notebooks." I tried this package and
found that it connects only to the external
LCD 20x4 display
, which is a LCD display connected to a serial
port. I can't see any use for a laptop yet, but you might use it to
build a wearable.
Diald Dial Daemon
provides on demand Internet connectivity
using the SLIP or PPP protocols. Diald can automatically dial
in to a remote host when needed or bring down dial-up
connections that are inactive.
Kcmlaptop. Written by Paul Campbell
kcmlaptop is a set of KDE control panels
that implements laptop computer support functions, it includes
a dockable battery status monitor for laptops - in short a
little icon in the KDE status bar that shows how much battery
time you have left. It also will warn you when power is
getting low and allows you to configure power saving options.
Similar packages you may find at the GNOME project
. See the software maps at both
Please see the
for further information.
Some more words about
disks spin down with noflushd or
hdparm utilities. The objective
is to reduce hard disk usage to minimum, because on most laptops it
is the primary source of noise and energy consumption. The "noflushd" daemon is a
replacement of "update" which makes buffer updates on disk only when
some other data is being read from the disk (the behavior of "update"
is to flush buffers every 5 seconds, and it usually generates
constant disk activity, so that the disk never becomes idle).
"noflushd" also sets the disk spindown time and automatically calls
"sync" before spindown. The syntax is something like "noflushd -n 5
/dev/hda". Using "noflushd" may cause loss of data if some files were
edited while the disk was parked and not sync'ed, e.g. if the power
was suddenly lost.
The hdparm utility can set the sleep time too, and also tune the
IDE disk parameters for better performance. Make sure that the
kernel IDE parameter "Use DMA by default when available" (section
"Block devices") is enabled.
However, it is not enough to enable noflushd
or IDE disk sleep time to make the disk
effectively silent, because the system in most
default installations is running many cron jobs, writes to log files,
uses swap and so on. This activity is not always desirable,
especially if the computer is standalone (not on network) and is used
mostly by one user. Here are some recommendations.
First, the cron daemon and friends (anacron, atd, logrotate,
sendmail / exim / ...) could be removed from the system if the
services they run (such as, cleaning /tmp directories and logs,
checking email etc.) are not needed.
Secondly, the syslogd configuration file
be modified to reduce the number of log files and messages
logged, and also to have "-" signs before every file name (which
means that the system will not have to sync the disk every time a
message is logged).
Also, it is advisable to add "mark:none;" to the "syslog" strings,
so that the "strich strich strich MARK strich strich strich"
messages do not get written to the log files every half an hour.
Typical Linux installations today have too many log files for the
Finally, the disk may not go to sleep when a lot of swap space is
in use. Type "free" and see how much swap is being used and how
much free RAM is available. If you think there is enough free RAM
to work without swap, or if there is a lot of swap used AND also
a lot of free RAM, consider freeing the swap space ("su; swapoff
-a; swapon -a") or switching the swap space off altogether ("su;
swapoff -a"). Working without swap should be fine on systems with
64MB or more of RAM. (Working without swap will reduce the
available memory, of course, and some software crashes without
warning when it runs out of memory. But, adding swap will not
prevent the crash resulting from some runaway memory consumuing
software, it will only delay it, and it will make the system swap
a lot before it happens.)
With these changes in the system, one could get the laptop to
work for extended periods of time with its hard disk switched
The kernel can be configured with "Yes" to "APM Support" and
"Enable console blanking using APM" (section "General setup").
Then the LCD screen lamp will shut off in console mode (so not
just the screen goes black, but also the lamp). In X mode, the
same effect can be obtained with "xset +dpms" (enable DPMS
function) and "xset s blank" (enable screen blanking). One can
add these commands to the X window session or window manager
The computer's BIOS energy savings options (hard disk sleep
time, video blanking time and so on) are probably not
useful and in some cases may even cause crashes. Therefore
they could be disabled in the laptop's BIOS.