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>
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