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Commit e495f78d authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'fib_trie-next' 



Alexander Duyck says:

====================
fib_trie: Reduce time spent in fib_table_lookup by 35 to 75%

These patches are meant to address several performance issues I have seen
in the fib_trie implementation, and fib_table_lookup specifically.  With
these changes in place I have seen a reduction of up to 35 to 75% for the
total time spent in fib_table_lookup depending on the type of search being
performed.

On a VM running in my Corei7-4930K system with a trie of maximum depth of 7
this resulted in a reduction of over 370ns per packet in the total time to
process packets received from an ixgbe interface and route them to a dummy
interface.  This represents a failed lookup in the local trie followed by
a successful search in the main trie.

				Baseline	Refactor
  ixgbe->dummy routing		1.20Mpps	2.21Mpps
  ------------------------------------------------------------
  processing time per packet		835ns		453ns
  fib_table_lookup		50.1%	418ns	25.0%	113ns
  check_leaf.isra.9		 7.9%	 66ns	   --	 --
  ixgbe_clean_rx_irq		 5.3%	 44ns	 9.8%	 44ns
  ip_route_input_noref		 2.9%	 25ns	 4.6%	 21ns
  pvclock_clocksource_read	 2.6%	 21ns	 4.6%	 21ns
  ip_rcv			 2.6%	 22ns	 4.0%	 18ns

In the simple case of receiving a frame and dropping it before it can reach
the socket layer I saw a reduction of 40ns per packet.  This represents a
trip through the local trie with the correct leaf found with no need for
any backtracing.

				Baseline	Refactor
  ixgbe->local receive		2.65Mpps	2.96Mpps
  ------------------------------------------------------------
  processing time per packet		377ns		337ns
  fib_table_lookup		25.1%	 95ns	25.8%	 87ns
  ixgbe_clean_rx_irq		 8.7%	 33ns	 9.0%	 30ns
  check_leaf.isra.9		 7.2%	 27ns	   --	 --
  ip_rcv			 5.7%	 21ns	 6.5%	 22ns

These changes have resulted in several functions being inlined such as
check_leaf and fib_find_node, but due to the code simplification the
overall size of the code has been reduced.

   text	   data	    bss	    dec	    hex	filename
  16932	    376	     16	  17324	   43ac	net/ipv4/fib_trie.o - before
  15259	    376	      8	  15643	   3d1b	net/ipv4/fib_trie.o - after

Changes since RFC:
  Replaced this_cpu_ptr with correct call to this_cpu_inc in patch 1
  Changed test for leaf_info mismatch to (key ^ n->key) & li->mask_plen in patch 10
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents bec94d43 5405afd1

include/net/ip_fib.h

+29 −21
Original line number Diff line number Diff line
@@ -222,16 +222,19 @@ static inline struct fib_table *fib_new_table(struct net *net, u32 id) 
static inline int fib_lookup(struct net *net, const struct flowi4 *flp,

			     struct fib_result *res)

{

	struct fib_table *table;

	int err = -ENETUNREACH;



	table = fib_get_table(net, RT_TABLE_LOCAL);

	if (!fib_table_lookup(table, flp, res, FIB_LOOKUP_NOREF))

		return 0;

	rcu_read_lock();



	table = fib_get_table(net, RT_TABLE_MAIN);

	if (!fib_table_lookup(table, flp, res, FIB_LOOKUP_NOREF))

		return 0;

	return -ENETUNREACH;

	if (!fib_table_lookup(fib_get_table(net, RT_TABLE_LOCAL), flp, res,

			      FIB_LOOKUP_NOREF) ||

	    !fib_table_lookup(fib_get_table(net, RT_TABLE_MAIN), flp, res,

			      FIB_LOOKUP_NOREF))

		err = 0;



	rcu_read_unlock();



	return err;

}



#else /* CONFIG_IP_MULTIPLE_TABLES */
@@ -247,20 +250,25 @@ static inline int fib_lookup(struct net *net, struct flowi4 *flp, 
			     struct fib_result *res)

{

	if (!net->ipv4.fib_has_custom_rules) {

		int err = -ENETUNREACH;



		rcu_read_lock();



		res->tclassid = 0;

		if (net->ipv4.fib_local &&

		if ((net->ipv4.fib_local &&

		     !fib_table_lookup(net->ipv4.fib_local, flp, res,

				      FIB_LOOKUP_NOREF))

			return 0;

		if (net->ipv4.fib_main &&

				       FIB_LOOKUP_NOREF)) ||

		    (net->ipv4.fib_main &&

		     !fib_table_lookup(net->ipv4.fib_main, flp, res,

				      FIB_LOOKUP_NOREF))

			return 0;

		if (net->ipv4.fib_default &&

				       FIB_LOOKUP_NOREF)) ||

		    (net->ipv4.fib_default &&

		     !fib_table_lookup(net->ipv4.fib_default, flp, res,

				      FIB_LOOKUP_NOREF))

			return 0;

		return -ENETUNREACH;

				       FIB_LOOKUP_NOREF)))

			err = 0;



		rcu_read_unlock();



		return err;

	}

	return __fib_lookup(net, flp, res);

}

net/ipv4/fib_frontend.c

+16 −13
Original line number Diff line number Diff line
@@ -67,7 +67,7 @@ static int __net_init fib4_rules_init(struct net *net) 
	return 0;



fail:

	kfree(local_table);

	fib_free_table(local_table);

	return -ENOMEM;

}

#else
@@ -109,6 +109,7 @@ struct fib_table *fib_new_table(struct net *net, u32 id) 
	return tb;

}



/* caller must hold either rtnl or rcu read lock */

struct fib_table *fib_get_table(struct net *net, u32 id)

{

	struct fib_table *tb;
@@ -119,15 +120,11 @@ struct fib_table *fib_get_table(struct net *net, u32 id) 
		id = RT_TABLE_MAIN;

	h = id & (FIB_TABLE_HASHSZ - 1);



	rcu_read_lock();

	head = &net->ipv4.fib_table_hash[h];

	hlist_for_each_entry_rcu(tb, head, tb_hlist) {

		if (tb->tb_id == id) {

			rcu_read_unlock();

		if (tb->tb_id == id)

			return tb;

	}

	}

	rcu_read_unlock();

	return NULL;

}

#endif /* CONFIG_IP_MULTIPLE_TABLES */
@@ -167,16 +164,18 @@ static inline unsigned int __inet_dev_addr_type(struct net *net, 
	if (ipv4_is_multicast(addr))

		return RTN_MULTICAST;



	rcu_read_lock();



	local_table = fib_get_table(net, RT_TABLE_LOCAL);

	if (local_table) {

		ret = RTN_UNICAST;

		rcu_read_lock();

		if (!fib_table_lookup(local_table, &fl4, &res, FIB_LOOKUP_NOREF)) {

			if (!dev || dev == res.fi->fib_dev)

				ret = res.type;

		}

		rcu_read_unlock();

	}



	rcu_read_unlock();

	return ret;

}
@@ -919,7 +918,7 @@ void fib_del_ifaddr(struct in_ifaddr *ifa, struct in_ifaddr *iprim) 
#undef BRD1_OK

}



static void nl_fib_lookup(struct fib_result_nl *frn, struct fib_table *tb)

static void nl_fib_lookup(struct net *net, struct fib_result_nl *frn)

{



	struct fib_result       res;
@@ -929,6 +928,11 @@ static void nl_fib_lookup(struct fib_result_nl *frn, struct fib_table *tb) 
		.flowi4_tos = frn->fl_tos,

		.flowi4_scope = frn->fl_scope,

	};

	struct fib_table *tb;



	rcu_read_lock();



	tb = fib_get_table(net, frn->tb_id_in);



	frn->err = -ENOENT;

	if (tb) {
@@ -945,6 +949,8 @@ static void nl_fib_lookup(struct fib_result_nl *frn, struct fib_table *tb) 
		}

		local_bh_enable();

	}



	rcu_read_unlock();

}



static void nl_fib_input(struct sk_buff *skb)
@@ -952,7 +958,6 @@ static void nl_fib_input(struct sk_buff *skb) 
	struct net *net;

	struct fib_result_nl *frn;

	struct nlmsghdr *nlh;

	struct fib_table *tb;

	u32 portid;



	net = sock_net(skb->sk);
@@ -967,9 +972,7 @@ static void nl_fib_input(struct sk_buff *skb) 
	nlh = nlmsg_hdr(skb);



	frn = (struct fib_result_nl *) nlmsg_data(nlh);

	tb = fib_get_table(net, frn->tb_id_in);



	nl_fib_lookup(frn, tb);

	nl_fib_lookup(net, frn);



	portid = NETLINK_CB(skb).portid;      /* netlink portid */

	NETLINK_CB(skb).portid = 0;        /* from kernel */

net/ipv4/fib_rules.c

+10 −12
Original line number Diff line number Diff line
@@ -81,27 +81,25 @@ static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp, 
		break;



	case FR_ACT_UNREACHABLE:

		err = -ENETUNREACH;

		goto errout;

		return -ENETUNREACH;



	case FR_ACT_PROHIBIT:

		err = -EACCES;

		goto errout;

		return -EACCES;



	case FR_ACT_BLACKHOLE:

	default:

		err = -EINVAL;

		goto errout;

		return -EINVAL;

	}



	rcu_read_lock();



	tbl = fib_get_table(rule->fr_net, rule->table);

	if (!tbl)

		goto errout;

	if (tbl)

		err = fib_table_lookup(tbl, &flp->u.ip4,

				       (struct fib_result *)arg->result,

				       arg->flags);



	err = fib_table_lookup(tbl, &flp->u.ip4, (struct fib_result *) arg->result, arg->flags);

	if (err > 0)

		err = -EAGAIN;

errout:

	rcu_read_unlock();

	return err;

}

net/ipv4/fib_trie.c

+891 −1025

File changed.

Preview size limit exceeded, changes collapsed.