netdev - [RFC PATCH 12/29] fib_trie: move leaf and tnode to occupy the same spot in the key vector

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Date:	Tue, 24 Feb 2015 12:49:15 -0800
From:	Alexander Duyck <alexander.h.duyck@...hat.com>
To:	netdev@...r.kernel.org
Subject: [RFC PATCH 12/29] fib_trie: move leaf and tnode to occupy the same
 spot in the key vector

If we are going to compact the leaf and tnode we first need to make sure
the fields are all in the same place.  In that regard I am moving the leaf
pointer which represents the fib_alias hash list to occupy what is
currently the first key_vector pointer.

Signed-off-by: Alexander Duyck <alexander.h.duyck@...hat.com>
---
 net/ipv4/fib_trie.c |   22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index cffbe47..caa2e28 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -94,21 +94,19 @@ typedef unsigned int t_key;
 #define get_index(_key, _kv) (((_key) ^ (_kv)->key) >> (_kv)->pos)
 
 struct key_vector {
+	struct rcu_head rcu;
+	t_key empty_children;		/* KEYLENGTH bits needed */
+	t_key full_children;		/* KEYLENGTH bits needed */
+	struct key_vector __rcu *parent;
 	t_key key;
 	unsigned char bits;		/* 2log(KEYLENGTH) bits needed */
 	unsigned char pos;		/* 2log(KEYLENGTH) bits needed */
 	unsigned char slen;
-	struct key_vector __rcu *parent;
-	struct rcu_head rcu;
 	union {
-		/* The fields in this struct are valid if bits > 0 (TNODE) */
-		struct {
-			t_key empty_children; /* KEYLENGTH bits needed */
-			t_key full_children;  /* KEYLENGTH bits needed */
-			struct key_vector __rcu *tnode[0];
-		};
 		/* This list pointer if valid if bits == 0 (LEAF) */
 		struct hlist_head leaf;
+		/* The fields in this struct are valid if bits > 0 (TNODE) */
+		struct key_vector __rcu *tnode[0];
 	};
 };
 
@@ -273,7 +271,7 @@ static inline void alias_free_mem_rcu(struct fib_alias *fa)
 	call_rcu(&fa->rcu, __alias_free_mem);
 }
 
-#define TNODE_SIZE sizeof(struct key_vector)
+#define TNODE_SIZE offsetof(struct key_vector, tnode[0])
 #define TNODE_KMALLOC_MAX \
 	ilog2((PAGE_SIZE - TNODE_SIZE) / sizeof(struct key_vector *))
 
@@ -1733,7 +1731,7 @@ void __init fib_trie_init(void)
 					  0, SLAB_PANIC, NULL);
 
 	trie_leaf_kmem = kmem_cache_create("ip_fib_trie",
-					   TNODE_SIZE,
+					   sizeof(struct key_vector),
 					   0, SLAB_PANIC, NULL);
 }
 
@@ -1891,7 +1889,7 @@ static void trie_show_stats(struct seq_file *seq, struct trie_stat *stat)
 	seq_printf(seq, "\tMax depth:      %u\n", stat->maxdepth);
 
 	seq_printf(seq, "\tLeaves:         %u\n", stat->leaves);
-	bytes = TNODE_SIZE * stat->leaves;
+	bytes = sizeof(struct key_vector) * stat->leaves;
 
 	seq_printf(seq, "\tPrefixes:       %u\n", stat->prefixes);
 	bytes += sizeof(struct fib_alias) * stat->prefixes;
@@ -1966,7 +1964,7 @@ static int fib_triestat_seq_show(struct seq_file *seq, void *v)
 	seq_printf(seq,
 		   "Basic info: size of leaf:"
 		   " %Zd bytes, size of tnode: %Zd bytes.\n",
-		   TNODE_SIZE, TNODE_SIZE);
+		   sizeof(struct key_vector), TNODE_SIZE);
 
 	for (h = 0; h < FIB_TABLE_HASHSZ; h++) {
 		struct hlist_head *head = &net->ipv4.fib_table_hash[h];

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