Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit f04565dd authored by Mihai Maruseac's avatar Mihai Maruseac Committed by David S. Miller
Browse files

dev: use name hash for dev_seq_ops 



Instead of using the dev->next chain and trying to resync at each call to
dev_seq_start, use the name hash, keeping the bucket and the offset in
seq->private field.

Tests revealed the following results for ifconfig > /dev/null
	* 1000 interfaces:
		* 0.114s without patch
		* 0.089s with patch
	* 3000 interfaces:
		* 0.489s without patch
		* 0.110s with patch
	* 5000 interfaces:
		* 1.363s without patch
		* 0.250s with patch
	* 128000 interfaces (other setup):
		* ~100s without patch
		* ~30s with patch

Signed-off-by: default avatarMihai Maruseac <mmaruseac@ixiacom.com>
Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e09eff7f

net/core/dev.c

+69 −15
Original line number Diff line number Diff line
@@ -4093,6 +4093,60 @@ static int dev_ifconf(struct net *net, char __user *arg) 
}



#ifdef CONFIG_PROC_FS



#define BUCKET_SPACE (32 - NETDEV_HASHBITS)



struct dev_iter_state {

	struct seq_net_private p;

	unsigned int pos; /* bucket << BUCKET_SPACE + offset */

};



#define get_bucket(x) ((x) >> BUCKET_SPACE)

#define get_offset(x) ((x) & ((1 << BUCKET_SPACE) - 1))

#define set_bucket_offset(b, o) ((b) << BUCKET_SPACE | (o))



static inline struct net_device *dev_from_same_bucket(struct seq_file *seq)

{

	struct dev_iter_state *state = seq->private;

	struct net *net = seq_file_net(seq);

	struct net_device *dev;

	struct hlist_node *p;

	struct hlist_head *h;

	unsigned int count, bucket, offset;



	bucket = get_bucket(state->pos);

	offset = get_offset(state->pos);

	h = &net->dev_name_head[bucket];

	count = 0;

	hlist_for_each_entry_rcu(dev, p, h, name_hlist) {

		if (count++ == offset) {

			state->pos = set_bucket_offset(bucket, count);

			return dev;

		}

	}



	return NULL;

}



static inline struct net_device *dev_from_new_bucket(struct seq_file *seq)

{

	struct dev_iter_state *state = seq->private;

	struct net_device *dev;

	unsigned int bucket;



	bucket = get_bucket(state->pos);

	do {

		dev = dev_from_same_bucket(seq);

		if (dev)

			return dev;



		bucket++;

		state->pos = set_bucket_offset(bucket, 0);

	} while (bucket < NETDEV_HASHENTRIES);



	return NULL;

}



/*

 *	This is invoked by the /proc filesystem handler to display a device

 *	in detail.
@@ -4100,33 +4154,33 @@ static int dev_ifconf(struct net *net, char __user *arg) 
void *dev_seq_start(struct seq_file *seq, loff_t *pos)

	__acquires(RCU)

{

	struct net *net = seq_file_net(seq);

	loff_t off;

	struct net_device *dev;

	struct dev_iter_state *state = seq->private;



	rcu_read_lock();

	if (!*pos)

		return SEQ_START_TOKEN;



	off = 1;

	for_each_netdev_rcu(net, dev)

		if (off++ == *pos)

			return dev;



	/* check for end of the hash */

	if (state->pos == 0 && *pos > 1)

		return NULL;



	return dev_from_new_bucket(seq);

}



void *dev_seq_next(struct seq_file *seq, void *v, loff_t *pos)

{

	struct net_device *dev = v;

	struct net_device *dev;



	++*pos;



	if (v == SEQ_START_TOKEN)

		dev = first_net_device_rcu(seq_file_net(seq));

	else

		dev = next_net_device_rcu(dev);

		return dev_from_new_bucket(seq);



	++*pos;

	dev = dev_from_same_bucket(seq);

	if (dev)

		return dev;



	return dev_from_new_bucket(seq);

}



void dev_seq_stop(struct seq_file *seq, void *v)
@@ -4225,7 +4279,7 @@ static const struct seq_operations dev_seq_ops = { 
static int dev_seq_open(struct inode *inode, struct file *file)

{

	return seq_open_net(inode, file, &dev_seq_ops,

			    sizeof(struct seq_net_private));

			    sizeof(struct dev_iter_state));

}



static const struct file_operations dev_seq_fops = {