Re: [PATCH] Add kallsyms_lookup() result cache

[Andrew Morton <akpm@osdl.org>]

Albert Cahalan <albert@users.sourceforge.net> wrote:
>
> > Doing the cache in the kernel is the wrong place. This should be fixed
>  > in user space.
> 
>  No way, because:
> 
>  1. kernel modules may be loaded or unloaded at any time

Poll /proc/modules?

>  2. the /proc/*/wchan files don't provide both name and address

/proc/stat has the address, /proc/kallsyms gives the symbol?

>  I'd be happy to make top (and the rest of procps) use a cache
>  if those problems were addressed. I need a signal sent on
>  module load/unload, or a real /proc/kallsyms st_mtime that I
>  can poll. I also need to have the numeric wchan address in
>  the /proc/*/wchan file, such that it is reliably the same
>  thing as the function name already found there.

Updating mtime on /proc/modules may be more logical, or even both.

Or put a modprobe sequence number somewhere in /proc and look for changes
in that.

It definitely needs to be fixed, but it doesn't seem that adding code to
the kernel is needed.