From: Eric Dumazet <dada1@cosmosbay.com>
Date: Thu, 7 Dec 2006 04:38:48 +0000 (-0800)
Subject: [PATCH] dcache: avoid RCU for never-hashed dentries
X-Git-Tag: v2.6.20-rc1~145^2^2~111
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b3423415fbc2e5461605826317da1c8dbbf21f97;p=pandora-kernel.git

[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>
---

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