On Tue, Sep 11, 2007 at 05:40:27PM +0200, Harald Hoyer wrote: > >A while back I did some experiments with systemtap and found that > >modprobe was doing a linear search through modules.deps: > > > >http://sourceware.org/ml/systemtap/2007-q1/msg00140.html > > > >I wrote a script that would prepend the modules that are actually used > >to the beginning of modules.dep to reduce the average length of search. > >This reduced the amount of data read (and time spent waiting for I/O) > >and slightly reduced the time to boot the machine. Bootchart samples > >process state periodically. Below is some of the data extracted from the > >bootchart samples: > > > > all states D state > > modprobe modprobe > > samples samples > >normal modules.dep 120 73 > >reordered modules.deps 63 27 > > > >Having to linearly through 250K of text in modules.dep each time a > >module is loaded doesn't seem very efficient. > > > > > >-Will > > > > Problem is, that most of the modprobes with a modalias are not existent and > so every line is parsed. If modules.dep searching really takes significant time, then there is always an option to precompile it into a more efficient format, e.g. more compact, with a hash table or whatever best matches modprobe's use. Jakub -- fedora-devel-list mailing list fedora-devel-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/fedora-devel-list
