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Commit 2c1409a0 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
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inetpeer: Optimize inet_getid() 



While investigating for network latencies, I found inet_getid() was a
contention point for some workloads, as inet_peer_idlock is shared
by all inet_getid() users regardless of peers.

One way to fix this is to make ip_id_count an atomic_t instead
of __u16, and use atomic_add_return().

In order to keep sizeof(struct inet_peer) = 64 on 64bit arches
tcp_ts_stamp is also converted to __u32 instead of "unsigned long".

Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 234b27c3

include/net/inetpeer.h

+5 −11
Original line number Diff line number Diff line
@@ -17,15 +17,15 @@ struct inet_peer { 
	/* group together avl_left,avl_right,v4daddr to speedup lookups */

	struct inet_peer	*avl_left, *avl_right;

	__be32			v4daddr;	/* peer's address */

	__u16			avl_height;

	__u16			ip_id_count;	/* IP ID for the next packet */

	__u32			avl_height;

	struct list_head	unused;

	__u32			dtime;		/* the time of last use of not

						 * referenced entries */

	atomic_t		refcnt;

	atomic_t		rid;		/* Frag reception counter */

	atomic_t		ip_id_count;	/* IP ID for the next packet */

	__u32			tcp_ts;

	unsigned long		tcp_ts_stamp;

	__u32			tcp_ts_stamp;

};



void			inet_initpeers(void) __init;
@@ -36,17 +36,11 @@ struct inet_peer *inet_getpeer(__be32 daddr, int create); 
/* can be called from BH context or outside */

extern void inet_putpeer(struct inet_peer *p);



extern spinlock_t inet_peer_idlock;

/* can be called with or without local BH being disabled */

static inline __u16	inet_getid(struct inet_peer *p, int more)

{

	__u16 id;



	spin_lock_bh(&inet_peer_idlock);

	id = p->ip_id_count;

	p->ip_id_count += 1 + more;

	spin_unlock_bh(&inet_peer_idlock);

	return id;

	more++;

	return atomic_add_return(more, &p->ip_id_count) - more;

}



#endif /* _NET_INETPEER_H */

net/ipv4/inetpeer.c

+1 −4
Original line number Diff line number Diff line
@@ -67,9 +67,6 @@ 
 *		ip_id_count: idlock

 */



/* Exported for inet_getid inline function.  */

DEFINE_SPINLOCK(inet_peer_idlock);



static struct kmem_cache *peer_cachep __read_mostly;



#define node_height(x) x->avl_height
@@ -390,7 +387,7 @@ struct inet_peer *inet_getpeer(__be32 daddr, int create) 
	n->v4daddr = daddr;

	atomic_set(&n->refcnt, 1);

	atomic_set(&n->rid, 0);

	n->ip_id_count = secure_ip_id(daddr);

	atomic_set(&n->ip_id_count, secure_ip_id(daddr));

	n->tcp_ts_stamp = 0;



	write_lock_bh(&peer_pool_lock);

net/ipv4/route.c

+1 −1
Original line number Diff line number Diff line
@@ -2852,7 +2852,7 @@ static int rt_fill_info(struct net *net, 
	error = rt->u.dst.error;

	expires = rt->u.dst.expires ? rt->u.dst.expires - jiffies : 0;

	if (rt->peer) {

		id = rt->peer->ip_id_count;

		id = atomic_read(&rt->peer->ip_id_count) & 0xffff;

		if (rt->peer->tcp_ts_stamp) {

			ts = rt->peer->tcp_ts;

			tsage = get_seconds() - rt->peer->tcp_ts_stamp;

net/ipv4/tcp_ipv4.c

+8 −8
Original line number Diff line number Diff line
@@ -204,7 +204,7 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) 
		 * when trying new connection.

		 */

		if (peer != NULL &&

		    peer->tcp_ts_stamp + TCP_PAWS_MSL >= get_seconds()) {

		    (u32)get_seconds() - peer->tcp_ts_stamp <= TCP_PAWS_MSL) {

			tp->rx_opt.ts_recent_stamp = peer->tcp_ts_stamp;

			tp->rx_opt.ts_recent = peer->tcp_ts;

		}
@@ -1308,7 +1308,7 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 
		    tcp_death_row.sysctl_tw_recycle &&

		    (peer = rt_get_peer((struct rtable *)dst)) != NULL &&

		    peer->v4daddr == saddr) {

			if (get_seconds() < peer->tcp_ts_stamp + TCP_PAWS_MSL &&

			if ((u32)get_seconds() - peer->tcp_ts_stamp < TCP_PAWS_MSL &&

			    (s32)(peer->tcp_ts - req->ts_recent) >

							TCP_PAWS_WINDOW) {

				NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSPASSIVEREJECTED);
@@ -1727,9 +1727,9 @@ int tcp_v4_remember_stamp(struct sock *sk) 


	if (peer) {

		if ((s32)(peer->tcp_ts - tp->rx_opt.ts_recent) <= 0 ||

		    (peer->tcp_ts_stamp + TCP_PAWS_MSL < get_seconds() &&

		     peer->tcp_ts_stamp <= tp->rx_opt.ts_recent_stamp)) {

			peer->tcp_ts_stamp = tp->rx_opt.ts_recent_stamp;

		    ((u32)get_seconds() - peer->tcp_ts_stamp > TCP_PAWS_MSL &&

		     peer->tcp_ts_stamp <= (u32)tp->rx_opt.ts_recent_stamp)) {

			peer->tcp_ts_stamp = (u32)tp->rx_opt.ts_recent_stamp;

			peer->tcp_ts = tp->rx_opt.ts_recent;

		}

		if (release_it)
@@ -1748,9 +1748,9 @@ int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw) 
		const struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);



		if ((s32)(peer->tcp_ts - tcptw->tw_ts_recent) <= 0 ||

		    (peer->tcp_ts_stamp + TCP_PAWS_MSL < get_seconds() &&

		     peer->tcp_ts_stamp <= tcptw->tw_ts_recent_stamp)) {

			peer->tcp_ts_stamp = tcptw->tw_ts_recent_stamp;

		    ((u32)get_seconds() - peer->tcp_ts_stamp > TCP_PAWS_MSL &&

		     peer->tcp_ts_stamp <= (u32)tcptw->tw_ts_recent_stamp)) {

			peer->tcp_ts_stamp = (u32)tcptw->tw_ts_recent_stamp;

			peer->tcp_ts	   = tcptw->tw_ts_recent;

		}

		inet_putpeer(peer);