From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexander Duyck Subject: [RFC PATCH 06/17] fib_trie: Optimize fib_find_node Date: Mon, 22 Dec 2014 09:41:30 -0800 Message-ID: <20141222174130.1119.85241.stgit@ahduyck-vm-fedora20> References: <20141222172632.1119.51469.stgit@ahduyck-vm-fedora20> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit To: netdev@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:41715 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755071AbaLVRlc (ORCPT ); Mon, 22 Dec 2014 12:41:32 -0500 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id sBMHfVnc021437 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Mon, 22 Dec 2014 12:41:31 -0500 Received: from [192.168.122.173] (ovpn-112-82.phx2.redhat.com [10.3.112.82]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id sBMHfU3c007943 for ; Mon, 22 Dec 2014 12:41:30 -0500 In-Reply-To: <20141222172632.1119.51469.stgit@ahduyck-vm-fedora20> Sender: netdev-owner@vger.kernel.org List-ID: This patch makes use of the same features I made use of for fib_table_lookup to streamline fib_find_node. The resultant code should be smaller and run faster than the original. Signed-off-by: Alexander Duyck --- net/ipv4/fib_trie.c | 36 +++++++++++++++++++++--------------- 1 file changed, 21 insertions(+), 15 deletions(-) diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c index fe2f60a..c182143 100644 --- a/net/ipv4/fib_trie.c +++ b/net/ipv4/fib_trie.c @@ -892,28 +892,34 @@ static void insert_leaf_info(struct hlist_head *head, struct leaf_info *new) } /* rcu_read_lock needs to be hold by caller from readside */ - static struct tnode *fib_find_node(struct trie *t, u32 key) { struct tnode *n = rcu_dereference_rtnl(t->trie); - int pos = 0; - while (n && IS_TNODE(n)) { - if (tkey_sub_equals(n->key, pos, n->pos-pos, key)) { - pos = n->pos + n->bits; - n = tnode_get_child_rcu(n, - tkey_extract_bits(key, - n->pos, - n->bits)); - } else + while (n) { + unsigned long index = get_index(key, n); + + /* This bit of code is a bit tricky but it combines multiple + * checks into a single check. The prefix consists of the + * prefix plus zeros for the bits in the cindex. The index + * is the difference between the key and this value. From + * this we can actually derive several pieces of data. + * if !(index >> bits) + * we know the value is cindex + * else + * we have a mismatch in skip bits and failed + */ + if (index >> n->bits) + return NULL; + + /* we have found a leaf. Prefixes have already been compared */ + if (IS_LEAF(n)) break; - } - /* Case we have found a leaf. Compare prefixes */ - if (n != NULL && IS_LEAF(n) && tkey_equals(key, n->key)) - return n; + n = rcu_dereference_rtnl(n->child[index]); + } - return NULL; + return n; } static void trie_rebalance(struct trie *t, struct tnode *tn)