[PATCH] Speed up modprobe and MAKEDEV

[Harald Hoyer]

Jon Masters wrote:
> On Mon, 2008-10-13 at 10:24 -0400, Jon Masters wrote:
>> On Mon, 2008-10-13 at 16:10 +0200, Jakub Jelinek wrote:
>>
>>> FYI, here is a tiny incremental fix for the patch I've posted earlier
>>> - Mandriva folks reported that with my patch depmod was upset when run
>>> on a tree with no modules at all.
>> :) Though if we ever manage to "demodularize for the win" to that point,
>> well, it'll be quite exciting!
>>
>> I'm testing your 3.4.1 patch against today's 3.5 tree and will followup
>> with some results. Whichever performs best, I'll keep. Sorry I didn't
>> sort this out sooner, but it's time to move forward and get this sorted
>> out - and there are more trivial fixes I've got in mind. As of today's
>> rawhide there are also no longer any Fedora-specific patches left.
> 
> In one test, I ran modprobe about 8000 times on a desktop.
> 
> older modprobe:       190.03user 25.19system 3:55.54elapsed 91%CPU
> upstream modprobe:      8.65user 19.69system 0:31.08elapsed 91%CPU
> Jakob's modprobe:       6.71user 18.05system 0:27.01elapsed 91%CPU
> 
> The latter two vie a little between each other, but basically are
> comparable. So for now, I'll keep upstream as it is and do some more
> testing/write some scripts. Then I'll do some migration to unlocked
> non-threaded functions and pull in other parts of Jakob's patch. I'm
> thinking there are actually other places to focus on now - more
> profiling will be called for and I'll push some more updates.
> 
> Older modprobe is 3.4.1, upstream is 3.5 (radix trie implementation),
> Jakob's patch uses a hashtable/bucket mechanism.
> 
> Jon.
> 
> 

modprobe is mostly disk I/O bound, so for benchmarking the disk cache has to be 
cleared before every run