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Commit 8315f5d8 authored by Stephen Hemminger's avatar Stephen Hemminger Committed by David S. Miller
Browse files

fib_trie: /proc/net/route performance improvement 



Use key/offset caching to change /proc/net/route (use by iputils route)
from O(n^2) to O(n). This improves performance from 30sec with 160,000
routes to 1sec.

Signed-off-by: default avatarStephen Hemminger <shemminger@vyatta.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ec28cf73

net/ipv4/fib_trie.c

+82 −11
Original line number Diff line number Diff line
@@ -2459,6 +2459,84 @@ static const struct file_operations fib_trie_fops = { 
	.release = seq_release_net,

};



struct fib_route_iter {

	struct seq_net_private p;

	struct trie *main_trie;

	loff_t	pos;

	t_key	key;

};



static struct leaf *fib_route_get_idx(struct fib_route_iter *iter, loff_t pos)

{

	struct leaf *l = NULL;

	struct trie *t = iter->main_trie;



	/* use cache location of last found key */

	if (iter->pos > 0 && pos >= iter->pos && (l = fib_find_node(t, iter->key)))

		pos -= iter->pos;

	else {

		iter->pos = 0;

		l = trie_firstleaf(t);

	}



	while (l && pos-- > 0) {

		iter->pos++;

		l = trie_nextleaf(l);

	}



	if (l)

		iter->key = pos;	/* remember it */

	else

		iter->pos = 0;		/* forget it */



	return l;

}



static void *fib_route_seq_start(struct seq_file *seq, loff_t *pos)

	__acquires(RCU)

{

	struct fib_route_iter *iter = seq->private;

	struct fib_table *tb;



	rcu_read_lock();

	tb = fib_get_table(iter->p.net, RT_TABLE_MAIN);

	if (!tb)

		return NULL;



	iter->main_trie = (struct trie *) tb->tb_data;

	if (*pos == 0)

		return SEQ_START_TOKEN;

	else

		return fib_route_get_idx(iter, *pos - 1);

}



static void *fib_route_seq_next(struct seq_file *seq, void *v, loff_t *pos)

{

	struct fib_route_iter *iter = seq->private;

	struct leaf *l = v;



	++*pos;

	if (v == SEQ_START_TOKEN) {

		iter->pos = 0;

		l = trie_firstleaf(iter->main_trie);

	} else {

		iter->pos++;

		l = trie_nextleaf(l);

	}



	if (l)

		iter->key = l->key;

	else

		iter->pos = 0;

	return l;

}



static void fib_route_seq_stop(struct seq_file *seq, void *v)

	__releases(RCU)

{

	rcu_read_unlock();

}



static unsigned fib_flag_trans(int type, __be32 mask, const struct fib_info *fi)

{

	static unsigned type2flags[RTN_MAX + 1] = {
@@ -2482,7 +2560,6 @@ static unsigned fib_flag_trans(int type, __be32 mask, const struct fib_info *fi) 
 */

static int fib_route_seq_show(struct seq_file *seq, void *v)

{

	const struct fib_trie_iter *iter = seq->private;

	struct leaf *l = v;

	struct leaf_info *li;

	struct hlist_node *node;
@@ -2494,12 +2571,6 @@ static int fib_route_seq_show(struct seq_file *seq, void *v) 
		return 0;

	}



	if (iter->trie == iter->trie_local)

		return 0;



	if (IS_TNODE(l))

		return 0;



	hlist_for_each_entry_rcu(li, node, &l->list, hlist) {

		struct fib_alias *fa;

		__be32 mask, prefix;
@@ -2542,16 +2613,16 @@ static int fib_route_seq_show(struct seq_file *seq, void *v) 
}



static const struct seq_operations fib_route_seq_ops = {

	.start  = fib_trie_seq_start,

	.next   = fib_trie_seq_next,

	.stop   = fib_trie_seq_stop,

	.start  = fib_route_seq_start,

	.next   = fib_route_seq_next,

	.stop   = fib_route_seq_stop,

	.show   = fib_route_seq_show,

};



static int fib_route_seq_open(struct inode *inode, struct file *file)

{

	return seq_open_net(inode, file, &fib_route_seq_ops,

			    sizeof(struct fib_trie_iter));

			    sizeof(struct fib_route_iter));

}



static const struct file_operations fib_route_fops = {