kernel modules and performance

[der.hans]

moin moin,

There is a performance hit for using modules rather than having the
functionality built in to the kernel. Is that a recurring penalty once the
module has been loaded? In other words, does the kernel have to do
something extra each time it uses a fx() from a module?

Does having a whole bunch of loaded modules cause a performance hit
because some module lookup table gets huge or for some other reason?

Does having unused modules that are available on the file system cause
a performance hit for the kernel? Module dependencies are stored on disk
and the modules aren't being used, so I think the downside would only be
that they use more disk space. Maybe the size of resources like a module
lookup table are determined at compile time such that having more modules
staticly dedicates more resources to handling them...

I realize this performance hits might be slight under most circumstances.
I want to understand whether or not they exist at all and then learn if
there are conditions where they are significant enough to be an issue.

ciao,

der.hans
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