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Re: modprobe slow linear search of /lib/modules/`uname -r`/modules.deps


William Cohen wrote:
> One of the thing that became
> apparent was the amount of data read from /lib/modules/`uname
> -r`/modules.dep and the time reading the data. modprobe is not smart
> at all about reading the file; it just does a linear search and stops
> when it finds the first matching entry.
> 
> Wouldn't it make sense to place the modules that are actually loaded
> at the beginning of the modules.dep to reduce the amount of data read
> by modprobe?
> 
> I wrote a simple script to examine the modules loaded and put the
> entries in modules.dep at the beginning of the file.  I then replaced
> the modules.dep with this modified version. I compared the data
> collected with bootchart.  The boot is a couple seconds faster for the
> modified version (1:05 vs 1:07) on AMD64 rawhide machine. 

This is interesting.  I'm not sure if there are embedded
developers using modprobe (you never know), but it still seems
interesting (both the immediate results and the technique)
for embedded folk.  Do you mind if I forward this to the
celinux-dev mailing list?
 -- Tim

=============================
Tim Bird
Architecture Group Chair, CE Linux Forum
Senior Staff Engineer, Sony Electronics
=============================


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