64 lines
1.9 KiB
Diff
64 lines
1.9 KiB
Diff
From: Alexander Duyck <alexander.h.duyck@redhat.com>
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Date: Wed, 31 Dec 2014 10:56:00 -0800
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Subject: [PATCH] fib_trie: Optimize fib_find_node
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This patch makes use of the same features I made use of for
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fib_table_lookup to streamline fib_find_node. The resultant code should be
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smaller and run faster than the original.
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Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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--- a/net/ipv4/fib_trie.c
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+++ b/net/ipv4/fib_trie.c
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@@ -892,28 +892,34 @@ static void insert_leaf_info(struct hlis
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}
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/* rcu_read_lock needs to be hold by caller from readside */
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-
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static struct tnode *fib_find_node(struct trie *t, u32 key)
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{
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struct tnode *n = rcu_dereference_rtnl(t->trie);
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- int pos = 0;
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- while (n && IS_TNODE(n)) {
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- if (tkey_sub_equals(n->key, pos, n->pos-pos, key)) {
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- pos = n->pos + n->bits;
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- n = tnode_get_child_rcu(n,
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- tkey_extract_bits(key,
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- n->pos,
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- n->bits));
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- } else
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+ while (n) {
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+ unsigned long index = get_index(key, n);
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+
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+ /* This bit of code is a bit tricky but it combines multiple
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+ * checks into a single check. The prefix consists of the
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+ * prefix plus zeros for the bits in the cindex. The index
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+ * is the difference between the key and this value. From
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+ * this we can actually derive several pieces of data.
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+ * if !(index >> bits)
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+ * we know the value is cindex
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+ * else
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+ * we have a mismatch in skip bits and failed
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+ */
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+ if (index >> n->bits)
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+ return NULL;
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+
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+ /* we have found a leaf. Prefixes have already been compared */
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+ if (IS_LEAF(n))
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break;
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- }
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- /* Case we have found a leaf. Compare prefixes */
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- if (n != NULL && IS_LEAF(n) && tkey_equals(key, n->key))
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- return n;
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+ n = rcu_dereference_rtnl(n->child[index]);
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+ }
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- return NULL;
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+ return n;
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}
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static void trie_rebalance(struct trie *t, struct tnode *tn)
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