[PATCH] dcache: avoid RCU for never-hashed dentries
authorEric Dumazet <dada1@cosmosbay.com>
Thu, 7 Dec 2006 04:38:48 +0000 (20:38 -0800)
committerLinus Torvalds <torvalds@woody.osdl.org>
Thu, 7 Dec 2006 16:39:41 +0000 (08:39 -0800)
commitb3423415fbc2e5461605826317da1c8dbbf21f97
treed7e129545515846526d72072322ad405a4b7a41b
parentd18de5a2721f84ffd6a5d637915746ed47becc1c
[PATCH] dcache: avoid RCU for never-hashed dentries

Some dentries don't need to be globally visible in dentry hashtable.
(pipes & sockets)

Such dentries dont need to wait for a RCU grace period at delete time.
Being able to free them permits a better CPU cache use (hot cache)

This patch combined with (dont insert pipe dentries into dentry_hashtable)
reduced time of { pipe(p); close(p[0]); close(p[1]);} on my UP machine (1.6
GHz Pentium-M) from 3.23 us to 2.86 us (But this patch does not depend on
other patches, only bench results)

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Maneesh Soni <maneesh@in.ibm.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Acked-by: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
fs/dcache.c