linux/scripts/basic
Eric Dumazet 8af27e1dc4 fixdep: use hash table instead of a single array
I noticed fixdep uses ~2% of cpu time in kernel build, in function
use_config()

fixdep spends a lot of cpu cycles in linear searches in its internal
string array. With about 400 stored strings per dep file, this begins to
be noticeable.

Convert fixdep to use a hash table.

kbuild results on my x86_64 allmodconfig

Before patch :

real	10m30.414s
user	61m51.456s
sys	8m28.200s

real	10m12.334s
user	61m50.236s
sys	8m30.448s

real	10m42.947s
user	61m50.028s
sys	8m32.380s

After:

real	10m8.180s
user	61m22.506s
sys	8m32.384s

real	10m35.039s
user	61m21.654s
sys	8m32.212s

real	10m14.487s
user	61m23.498s
sys	8m32.312s

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>
2010-11-11 17:12:06 +01:00
..
.gitignore Update .gitignore files for generated targets 2008-10-20 11:24:31 -07:00
docproc.c kbuild: add static to prototypes 2009-09-20 12:27:44 +02:00
fixdep.c fixdep: use hash table instead of a single array 2010-11-11 17:12:06 +01:00
hash.c kbuild: add static to prototypes 2009-09-20 12:27:44 +02:00
Makefile driver core: basic infrastructure for per-module dynamic debug messages 2008-10-16 09:24:47 -07:00