very common kernel modules slow down the boot process

Don Dutile ddutile at redhat.com
Wed Apr 2 14:28:12 UTC 2008



Chris Snook wrote:
> Harald Hoyer wrote:
>> Compiling these modules, which are loaded on nearly every PC, in the 
>> kernel cuts down my boot time from 42s to 32s on my computer:
>>
>> ata_generic
>> ata_piix
>> cdrom
>> dm_mirror
>> dm_mod
>> dm_snapshot
>> dm_zero
>> ehci_hcd
>> ext3
>> floppy
>> i2c_core
>> jbd
>> libata
>> mbcache
>> ohci_hcd
>> parport
>> parport_pc
>> pata_acpi
>> scsi_mod
>> sd_mod
>> sg
>> snd
>> snd_mixer_oss
>> snd_page_alloc
>> snd_pcm
>> snd_pcm_oss
>> snd_seq
>> snd_seq_device
>> snd_seq_dummy
>> snd_seq_midi_event
>> snd_seq_oss
>> snd_timer
>> soundcore
>> sr_mod
>> uhci_hcd
>>
> 
> It also makes it much more difficult to troubleshoot those subsystems or 
> work around their quirks.  I wouldn't have a problem with ext3, jbd, or 
> dm_* being built-in, but anything that deals with hardware should really 
> be modular.  Of course, that wipes out most of your list.
> 
> I'd really rather focus on optimizing modprobe than sacrificing the many 
> benefits of modularity for a very small performance boost.
> 
> -- Chris
> 
+1: do not hardwire hardware-based modules.

This is causing virtualization a bit of heartburn in RHEL4 & RHEL5, where IDE is
wired into the kernels, but we'd like to run them as FV guests, and cannot
(easily configure) the systems to not use emulated-IDE as the boot disk
(can't use pv-block driver for kernel/boot disk).  Fedora(8 & 9) don't have
the wired-in IDE, so it makes it easy(er) to use a FV guest (and added PV drivers).
So, let's not take a step backward and wire-in IDE/[,P,S]ATA.

- Don

ps -- if you want to focus on something, how about delaying the loading
       of non-boot-essential drivers: sound, bluetooth, etc.
       -- I can see the need for USB for serial-console on non-legacy machines.
     -- non-boot-essential daemon startup would be my next recommendation
        (see anything to do w/networking daemons...)






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