From: Eric Dumazet <dada1-fPLkHRcR87vqlBn2x/YWAg@public.gmane.org>
Date: Thu, 27 Nov 2008 00:32:41 +0100

Goal of this patch is to not touch inode_lock for socket/pipes/anonfd
 inodes allocation/freeing.

 In new_inode(), we test if super block has MS_SPECIAL flag set.
 If yes, we dont put inode in "inode_in_use" list nor "sb->s_inodes" list
 As inode_lock was taken only to protect these lists, we avoid it as well

 Using iput_special() from dput_special() avoids taking inode_lock
 at freeing time.

 This patch has a very noticeable effect, because we avoid dirtying of three contended cache lines in new_inode(), and five cache lines
 in iput()

Note: Not sure if we can use MS_SPECIAL=MS_NOUSER, or if we
really need a different flag.

(socket8 bench result : from 20.5s to 2.94s) 

Signed-off-by: Eric Dumazet <dada1-fPLkHRcR87vqlBn2x/YWAg@public.gmane.org>

No problem with networking part:

Acked-by: David S. Miller <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>