Kernel performance: 'to module' or not 'to module'?

[dlworld]

Hi all,

After compiling my kernel (several times) setting up my USB hard drive, I noticed that putting the drivers directly into the kernel (instead of making them modules), my kernel speed up a lot! Anyway, I'm not pretty sure, 'cause I changed many options, not only this module stuff... I also noticed that changing my root partition into reiserfs makes it go smoother too.

I want to know what's the truth behind this... is this a mere coincidence?

[Slammer]

I don't know about speed difference between builtin modules and loadable modules, but as general rule, I build in the kernel all options are needed for boot sequence (filesystems etc...) and as loadable modules all other device drivers. I also build some more modules for devices that I dont have (for example, the module for my nic card and some other popular nic cards, to make sure that if I change my card to be ready to go...)

For reiserfs, I also notice that reiserfs is much faster and smoother than ext3.

[chrispy]

There won't be any noticeable speed difference between a built-in module and a loadable module. that is, once everything you need is loaded into memory. indeed, boot time will be shorter if you choose to build less stuff within the kernel itself.

Of course, for boot-sequence needed stuff, you have to compile the option in the kernel. for everything else, I think it's better to build as loadable module simply because you can pass arguments/options to them on load, thing that you CANNOT do with built-in modules.