> * BUY LOTS OF RAM! DON'T USE A SWAP, especially when running off the
> battery.
But you need swap for suspend to disk to work. :) If you truly have
enough ram, swap won't hurt. In fact, if you let unused stuff swap out,
that means all the more RAM is available to cache files that actually
ARE in use, thus REDUCING overall disk access. Trust in swap, swap is
your friend.
> * (DANGEROUS) Turn on async for the filesystem. This allows the fs to
> write asynchronously instead of synchronously (may be default anyway)
This has always been default for Linux since the beginning of time. BSD
weenies have been bashing Linux for this just as long.
> * (DANGEROUS) Turn off dirsync for the filesystem. Same "benefits" as
> 'async'.
Also not on unless you turned it on.
> * (DANGEROUS) Selectively turn on/off journaling for an filesystem
> based on power management. This involves customizing the acpid or
> apmd scripts to remount filesystems in /etc/fstab that originally
> have the 'noload' option for ext3 or 'nolog' option for reiserfs.
This is wrong and ugly. Use laptop mode. Note that just "echo 1 >
/proc/sys/vm/laptop_mode" that the FC1 APM scripts do isn't good enough.
There's a script in your kernel source, in
"Documentation/laptop-mode.txt" that will remount all your filesystems
with the journal sync time extended, as well as tweaking some other
stuff in the VM to match. Laptop mode gains you nothing without these
options properly set as well. This is the Right Way(TM) to deal with
journaling on laptops.
I hacked up an apmcontinue script to properly enable/disable laptop mode
on Fedora Core 1. Here is my /etc/sysconfig/apm-scripts/apmcontinue :
#!/bin/bash
PROG="$1"
function laptop_mode_startstop
{
if apm |grep on-line &>/dev/null; then
beep -f 1000 -n -f 2000&
logger -i -p local0.info -t apm Disabling laptop mode
hdparm -B255 -S12 /dev/hda > /dev/null
/usr/local/sbin/laptop_mode stop
else
beep -f 2000 -n -f 1000&
logger -i -p local0.info -t apm Enabling laptop mode
hdparm -B0 -S4 /dev/hda > /dev/null
/usr/local/sbin/laptop_mode start
fi
}
case "$PROG" in
suspend|standby)
beep -f 500 -l 75 -r 2&
;;
resume|start)
laptop_mode_startstop
;;
stop)
;;
change)
case $2 in
power)
# change in power status
laptop_mode_startstop
;;
battery)
# battery low
beep -f 10000 -r 5&
logger -i -p local0.info -t apm Battery is low.
sync
;;
*)
beep -f 5000 -l 20 -d 20 -r 8&
logger -i -p local0.info -t apm Unknown message: change to
$2
;;
esac
;;
*)
beep -f 5000 -l 20 -d 20 -r 8&
logger -i -p local0.info -t apm Unknown message: $PROG
;;
esac
Note, this needs the laptop_mode script from your kernel source in
/usr/local/sbin. It varies depending on kernel version, so get it from
the kernel you're actually using. I also use "beep" to do a lot of
obnoxious beeping, get it from http://www.johnath.com/beep/
> * Turn down logging to a bare minimum. Throw away unimportant log
> entries in syslogd configuration or syslog-ng configuration.
My /etc/syslog.conf contains only:
*.* -/var/log/syslog
This just dumps everything to /var/log/syslog without syncing, laptop
mode will prevent the disk from spinning up, but you'll still get logs
as long as your battery doesn't die.
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