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96 lines
2.9 KiB
96 lines
2.9 KiB
10 years ago
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From: Alexander Duyck <alexander.h.duyck@redhat.com>
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Date: Wed, 31 Dec 2014 10:57:02 -0800
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Subject: [PATCH] fib_trie: Remove checks for index >= tnode_child_length
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from tnode_get_child
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For some reason the compiler doesn't seem to understand that when we are in
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a loop that runs from tnode_child_length - 1 to 0 we don't expect the value
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of tn->bits to change. As such every call to tnode_get_child was rerunning
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tnode_chile_length which ended up consuming quite a bit of space in the
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resultant assembly code.
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I have gone though and verified that in all cases where tnode_get_child
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is used we are either winding though a fixed loop from tnode_child_length -
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1 to 0, or are in a fastpath case where we are verifying the value by
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either checking for any remaining bits after shifting index by bits and
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testing for leaf, or by using tnode_child_length.
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size net/ipv4/fib_trie.o
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Before:
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text data bss dec hex filename
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15506 376 8 15890 3e12 net/ipv4/fib_trie.o
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After:
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text data bss dec hex filename
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14827 376 8 15211 3b6b net/ipv4/fib_trie.o
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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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@@ -186,8 +186,6 @@ static inline unsigned long tnode_child_
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static inline struct tnode *tnode_get_child(const struct tnode *tn,
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unsigned long i)
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{
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- BUG_ON(i >= tnode_child_length(tn));
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-
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return rtnl_dereference(tn->child[i]);
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}
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@@ -195,8 +193,6 @@ static inline struct tnode *tnode_get_ch
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static inline struct tnode *tnode_get_child_rcu(const struct tnode *tn,
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unsigned long i)
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{
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- BUG_ON(i >= tnode_child_length(tn));
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-
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return rcu_dereference_rtnl(tn->child[i]);
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}
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@@ -371,7 +367,7 @@ static inline int tnode_full(const struc
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*/
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static void put_child(struct tnode *tn, unsigned long i, struct tnode *n)
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{
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- struct tnode *chi = rtnl_dereference(tn->child[i]);
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+ struct tnode *chi = tnode_get_child(tn, i);
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int isfull, wasfull;
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BUG_ON(i >= tnode_child_length(tn));
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@@ -867,7 +863,7 @@ static struct tnode *fib_find_node(struc
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if (IS_LEAF(n))
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break;
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- n = rcu_dereference_rtnl(n->child[index]);
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+ n = tnode_get_child_rcu(n, index);
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}
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return n;
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@@ -934,7 +930,7 @@ static struct list_head *fib_insert_node
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}
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tp = n;
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- n = rcu_dereference_rtnl(n->child[index]);
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+ n = tnode_get_child_rcu(n, index);
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}
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l = leaf_new(key);
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@@ -1215,7 +1211,7 @@ int fib_table_lookup(struct fib_table *t
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cindex = index;
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}
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- n = rcu_dereference(n->child[index]);
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+ n = tnode_get_child_rcu(n, index);
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if (unlikely(!n))
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goto backtrace;
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}
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@@ -1835,7 +1831,7 @@ static void trie_collect_stats(struct tr
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if (n->bits < MAX_STAT_DEPTH)
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s->nodesizes[n->bits]++;
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- for (i = 0; i < tnode_child_length(n); i++) {
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+ for (i = tnode_child_length(n); i--;) {
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if (!rcu_access_pointer(n->child[i]))
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s->nullpointers++;
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}
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