very common kernel modules slow down the boot process

Harald Hoyer harald at redhat.com
Wed Apr 2 08:06:53 UTC 2008


Harald Hoyer wrote:
> Harald Hoyer wrote:
>> 39 seconds normal boot time on my system with modprobe of all modules.
>>
>> Now a measurement without modprobe:
>>
>> # mkinitrd -f  $(/sbin/lsmod |while read a b; do echo --preload 
>> $a;done|fgrep -v Module) /boot/initrd-$(uname -r).img $(uname -r)
>>
>> initrd now loads all used modules and we can disable modprobe:
>>
>> # mv /etc/udev/rules.d/80-drivers.rules 
>> /etc/udev/rules.d/80-drivers.rules.bak
>>
>> Now the boot time is 36 seconds.
>>
>> So, you can shave off a maximum of 3s with modprobe optimization on my 
>> system. Also a "small" performance boost.
>>
> 
> Also very interesting: if I turn on modprobe again, it takes 38 seconds.
> So 2 seconds for already loaded / non existent modules.
> 

standard: 39s total, 12s until rc.sysinit starts

If I compile in all modules, that can be compiled in: 35s total, 8s until rc.sysinit starts

Which means, I lose 4 seconds by loading ata_piix, dm_* modules in nash.

Blacklisting the rest of the modules (mostly sound) : 32s total, 8s until rc.sysinit starts


4 seconds in nash. Thats a lot just for loading some modules to mount my root partition.




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