[solved] fastboot and rootdelay kernel option

Question

hi to all,
i was reading about improving boot time in our archwiki. it says to append in /boot/grub/menu.lst two ''magic'' words:
fastboot
and
rootdelay=N
where N are seconds to wait before mount the root.
then i modify my .lst and perform a boot timing BUT results are exactly the same , the same time with or without these kernel option.....
my menu.lst:
# (0) Arch Linux NORMAL
title Arch Linux
root (hd0,0)
kernel /vmlinuz26 root=/dev/sda4 ro fastboot rootdelay=1 vga=773
initrd /kernel26.img
# (3) Arch Linux BOOTCHART
title Arch Linux Bootchart
root (hd0,0)
kernel /vmlinuz26 root=/dev/sda4 ro fastboot rootdelay=1 vga=773 init=/sbin/bootchartd
initrd /kernel26.img
# (1) Arch Linux FALLBACK
title Arch Linux Fallback
root (hd0,0)
kernel /vmlinuz26 root=/dev/disk/by-uuid/87011ee4-6d50-4384-a305-0a23d3f27588 ro
initrd /kernel26-fallback.img
# (4) RescueCD 64bit RESCUE
title SystemRescueCd from Hard Disk
root (hd0,0)
kernel /sysrcd/rescue64 subdir=sysrcd setkmap=it
initrd /sysrcd/initram.igz
where i make a mistake ?
thks
Last edited by nTia89 (2010-08-04 19:01:16)

Answer 1

Kernel command line parameters aren't inherently magical. fastboot was introduced in 2.6.29 and attempts to decrease boot time by performing some functions asynchronously. It may not result in anything speeding up. It may break things. It's probably not worth using.
Regarding rootdelay: The Wiki comes to a flawed conclusion that a shorter rootdelay will decrease boot time. rootdelay defines the maximum number of seconds the kernel is willing to wait for the root device to be mounted. It doesn't define an absolute time frame. rootdelay=100 will very likely yield the same results as rootdelay=10 because the boot process continues as soon as the root device is available. The wiki does correctly point out that a lower rootdelay can actually break the boot process.
To answer your question: your mistake is playing with parameters that you don't understand.
Last edited by falconindy (2010-08-04 18:08:42)