[lug] Loadable modules vs in-kernel

[D. Stimits]

Budyanto Himawan wrote:
> Hi,
> 
> Are there any runtime overheads in using loadable
> modules as opposed to in-kernel?

I can't tell you how much overhead there is, but there is always 
load-time overhead in loadable modules. If the module is already loaded, 
then at most there would probably be 1 more pointer to dereference, but 
possibly not even that. The first use and load of the module might have 
a noticeable impact (and probably does) in any module loader, but in a 
C-based scheme as well tested as the kernel I doubt there is any runtime 
impact that can be measured as "significant". Usually non-module use is 
chosen for reasons of security or boot-up reasons and not because of 
performance.

D. Stimits, stimits AT comcast DOT net