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Commit e9bf3b07 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'tunnel_dst_caching' 



Tom Herbert says:

====================
ipv4: Cache dst in tunnels

Version 3 of caching routes in tunnels.

Addressed some comments from Eric in this series.

There are two patches (variants) in the series:
1) One dst cached for each tunnel.
2) Percpu dst cache per tunnel to avoid false sharing

Testing with GRE tunnels on a 32 CPU host with bnx2x (RSS support
for GRE) shows a modest improvement in CPU utilization with these
patches running 200 TCP_RR netperf clients.

Without patches
71.22% CPU utilization
138/180/244 90/95/99% latencies
1.30465e+06 CPU/tps
18318 CPU/tps

With patches
69.84%
142/186/249 90/95/99% latencies
1.30827e+06
18732 CPU/tps
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents f916ec96 9a4aa9af

include/net/ip_tunnels.h

+7 −0
Original line number Diff line number Diff line
@@ -38,6 +38,11 @@ struct ip_tunnel_prl_entry { 
	struct rcu_head			rcu_head;

};



struct ip_tunnel_dst {

	struct dst_entry __rcu 		*dst;

	spinlock_t			lock;

};



struct ip_tunnel {

	struct ip_tunnel __rcu	*next;

	struct hlist_node hash_node;
@@ -54,6 +59,8 @@ struct ip_tunnel { 
	int		hlen;		/* Precalculated header length */

	int		mlink;



	struct ip_tunnel_dst __percpu *dst_cache;



	struct ip_tunnel_parm parms;



	/* for SIT */

net/ipv4/ip_tunnel.c

+109 −24
Original line number Diff line number Diff line
@@ -68,6 +68,63 @@ static unsigned int ip_tunnel_hash(struct ip_tunnel_net *itn, 
			 IP_TNL_HASH_BITS);

}



static inline void __tunnel_dst_set(struct ip_tunnel_dst *idst,

				    struct dst_entry *dst)

{

	struct dst_entry *old_dst;



	if (dst && (dst->flags & DST_NOCACHE))

		dst = NULL;



	spin_lock_bh(&idst->lock);

	old_dst = rcu_dereference(idst->dst);

	rcu_assign_pointer(idst->dst, dst);

	dst_release(old_dst);

	spin_unlock_bh(&idst->lock);

}



static inline void tunnel_dst_set(struct ip_tunnel *t, struct dst_entry *dst)

{

	__tunnel_dst_set(this_cpu_ptr(t->dst_cache), dst);

}



static inline void tunnel_dst_reset(struct ip_tunnel *t)

{

	tunnel_dst_set(t, NULL);

}



static void tunnel_dst_reset_all(struct ip_tunnel *t)

{

	int i;



	for_each_possible_cpu(i)

		__tunnel_dst_set(per_cpu_ptr(t->dst_cache, i), NULL);

}



static inline struct dst_entry *tunnel_dst_get(struct ip_tunnel *t)

{

	struct dst_entry *dst;



	rcu_read_lock();

	dst = rcu_dereference(this_cpu_ptr(t->dst_cache)->dst);

	if (dst)

		dst_hold(dst);

	rcu_read_unlock();

	return dst;

}



struct dst_entry *tunnel_dst_check(struct ip_tunnel *t, u32 cookie)

{

	struct dst_entry *dst = tunnel_dst_get(t);



	if (dst && dst->obsolete && dst->ops->check(dst, cookie) == NULL) {

		tunnel_dst_reset(t);

		return NULL;

	}



	return dst;

}



/* Often modified stats are per cpu, other are shared (netdev->stats) */

struct rtnl_link_stats64 *ip_tunnel_get_stats64(struct net_device *dev,

						struct rtnl_link_stats64 *tot)
@@ -318,8 +375,7 @@ static struct net_device *__ip_tunnel_create(struct net *net, 
	return ERR_PTR(err);

}



static inline struct rtable *ip_route_output_tunnel(struct net *net,

						    struct flowi4 *fl4,

static inline void init_tunnel_flow(struct flowi4 *fl4,

				    int proto,

				    __be32 daddr, __be32 saddr,

				    __be32 key, __u8 tos, int oif)
@@ -331,7 +387,6 @@ static inline struct rtable *ip_route_output_tunnel(struct net *net, 
	fl4->flowi4_tos = tos;

	fl4->flowi4_proto = proto;

	fl4->fl4_gre_key = key;

	return ip_route_output_key(net, fl4);

}



static int ip_tunnel_bind_dev(struct net_device *dev)
@@ -350,14 +405,14 @@ static int ip_tunnel_bind_dev(struct net_device *dev) 
		struct flowi4 fl4;

		struct rtable *rt;



		rt = ip_route_output_tunnel(tunnel->net, &fl4,

					    tunnel->parms.iph.protocol,

					    iph->daddr, iph->saddr,

					    tunnel->parms.o_key,

					    RT_TOS(iph->tos),

					    tunnel->parms.link);

		init_tunnel_flow(&fl4, iph->protocol, iph->daddr,

				 iph->saddr, tunnel->parms.o_key,

				 RT_TOS(iph->tos), tunnel->parms.link);

		rt = ip_route_output_key(tunnel->net, &fl4);



		if (!IS_ERR(rt)) {

			tdev = rt->dst.dev;

			tunnel_dst_set(tunnel, dst_clone(&rt->dst));

			ip_rt_put(rt);

		}

		if (dev->type != ARPHRD_ETHER)
@@ -528,10 +583,11 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev, 
	struct flowi4 fl4;

	u8     tos, ttl;

	__be16 df;

	struct rtable *rt;		/* Route to the other host */

	struct rtable *rt = NULL;	/* Route to the other host */

	unsigned int max_headroom;	/* The extra header space needed */

	__be32 dst;

	int err;

	bool connected = true;



	inner_iph = (const struct iphdr *)skb_inner_network_header(skb);
@@ -581,27 +637,39 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev, 
#endif

		else

			goto tx_error;



		connected = false;

	}



	tos = tnl_params->tos;

	if (tos & 0x1) {

		tos &= ~0x1;

		if (skb->protocol == htons(ETH_P_IP))

		if (skb->protocol == htons(ETH_P_IP)) {

			tos = inner_iph->tos;

		else if (skb->protocol == htons(ETH_P_IPV6))

			connected = false;

		} else if (skb->protocol == htons(ETH_P_IPV6)) {

			tos = ipv6_get_dsfield((const struct ipv6hdr *)inner_iph);

			connected = false;

		}

	}



	init_tunnel_flow(&fl4, protocol, dst, tnl_params->saddr,

			 tunnel->parms.o_key, RT_TOS(tos), tunnel->parms.link);



	if (connected)

		rt = (struct rtable *)tunnel_dst_check(tunnel, 0);



	if (!rt) {

		rt = ip_route_output_key(tunnel->net, &fl4);



	rt = ip_route_output_tunnel(tunnel->net, &fl4,

				    protocol,

				    dst, tnl_params->saddr,

				    tunnel->parms.o_key,

				    RT_TOS(tos),

				    tunnel->parms.link);

		if (IS_ERR(rt)) {

			dev->stats.tx_carrier_errors++;

			goto tx_error;

		}

		if (connected)

			tunnel_dst_set(tunnel, dst_clone(&rt->dst));

	}



	if (rt->dst.dev == dev) {

		ip_rt_put(rt);

		dev->stats.collisions++;
@@ -696,6 +764,7 @@ static void ip_tunnel_update(struct ip_tunnel_net *itn, 
		if (set_mtu)

			dev->mtu = mtu;

	}

	tunnel_dst_reset_all(t);

	netdev_state_change(dev);

}
@@ -811,6 +880,7 @@ static void ip_tunnel_dev_free(struct net_device *dev) 
	struct ip_tunnel *tunnel = netdev_priv(dev);



	gro_cells_destroy(&tunnel->gro_cells);

	free_percpu(tunnel->dst_cache);

	free_percpu(dev->tstats);

	free_netdev(dev);

}
@@ -989,8 +1059,21 @@ int ip_tunnel_init(struct net_device *dev) 
		u64_stats_init(&ipt_stats->syncp);

	}



	tunnel->dst_cache = alloc_percpu(struct ip_tunnel_dst);

	if (!tunnel->dst_cache) {

		free_percpu(dev->tstats);

		return -ENOMEM;

	}



	for_each_possible_cpu(i) {

		struct ip_tunnel_dst *idst = per_cpu_ptr(tunnel->dst_cache, i);

		idst-> dst = NULL;

		spin_lock_init(&idst->lock);

	}



	err = gro_cells_init(&tunnel->gro_cells, dev);

	if (err) {

		free_percpu(tunnel->dst_cache);

		free_percpu(dev->tstats);

		return err;

	}
@@ -1015,6 +1098,8 @@ void ip_tunnel_uninit(struct net_device *dev) 
	/* fb_tunnel_dev will be unregisted in net-exit call. */

	if (itn->fb_tunnel_dev != dev)

		ip_tunnel_del(netdev_priv(dev));



	tunnel_dst_reset_all(tunnel);

}

EXPORT_SYMBOL_GPL(ip_tunnel_uninit);