Commit 243bbcaa authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

[IPV4]: Optimize inet_getpeer() 



1) Some sysctl vars are declared __read_mostly

2) We can avoid updating stack[] when doing an AVL lookup only.

    lookup() macro is extended to receive a second parameter, that may be NULL
in case of a pure lookup (no need to save the AVL path). This removes
unnecessary instructions, because compiler knows if this _stack parameter is
NULL or not.

    text size of net/ipv4/inetpeer.o is 2063 bytes instead of 2107 on x86_64

Signed-off-by: default avatarEric Dumazet <dada1@cosmosbay.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 43e68392

net/ipv4/inetpeer.c

+22 −16
Original line number Diff line number Diff line
@@ -87,10 +87,12 @@ static DEFINE_RWLOCK(peer_pool_lock); 


static int peer_total;

/* Exported for sysctl_net_ipv4.  */

int inet_peer_threshold = 65536 + 128;	/* start to throw entries more

int inet_peer_threshold __read_mostly = 65536 + 128;	/* start to throw entries more

					 * aggressively at this stage */

int inet_peer_minttl = 120 * HZ;	/* TTL under high load: 120 sec */

int inet_peer_maxttl = 10 * 60 * HZ;	/* usual time to live: 10 min */

int inet_peer_minttl __read_mostly = 120 * HZ;	/* TTL under high load: 120 sec */

int inet_peer_maxttl __read_mostly = 10 * 60 * HZ;	/* usual time to live: 10 min */

int inet_peer_gc_mintime __read_mostly = 10 * HZ;

int inet_peer_gc_maxtime __read_mostly = 120 * HZ;



static struct inet_peer *inet_peer_unused_head;

static struct inet_peer **inet_peer_unused_tailp = &inet_peer_unused_head;
@@ -99,9 +101,6 @@ static DEFINE_SPINLOCK(inet_peer_unused_lock); 
static void peer_check_expire(unsigned long dummy);

static DEFINE_TIMER(peer_periodic_timer, peer_check_expire, 0, 0);



/* Exported for sysctl_net_ipv4.  */

int inet_peer_gc_mintime = 10 * HZ,

    inet_peer_gc_maxtime = 120 * HZ;



/* Called from ip_output.c:ip_init  */

void __init inet_initpeers(void)
@@ -151,19 +150,26 @@ static void unlink_from_unused(struct inet_peer *p) 
	spin_unlock_bh(&inet_peer_unused_lock);

}



/* Called with local BH disabled and the pool lock held. */

#define lookup(daddr) 						\

/*

 * Called with local BH disabled and the pool lock held.

 * _stack is known to be NULL or not at compile time,

 * so compiler will optimize the if (_stack) tests.

 */

#define lookup(_daddr,_stack) 					\

({								\

	struct inet_peer *u, **v;				\

	stackptr = stack;					\

	if (_stack) {						\

		stackptr = _stack;				\

		*stackptr++ = &peer_root;			\

	}							\

	for (u = peer_root; u != peer_avl_empty; ) {		\

		if (daddr == u->v4daddr)			\

		if (_daddr == u->v4daddr)			\

			break;					\

		if ((__force __u32)daddr < (__force __u32)u->v4daddr)	\

		if ((__force __u32)_daddr < (__force __u32)u->v4daddr)	\

			v = &u->avl_left;			\

		else						\

			v = &u->avl_right;			\

		if (_stack)					\

			*stackptr++ = v;			\

		u = *v;						\

	}							\
@@ -288,7 +294,7 @@ static void unlink_from_pool(struct inet_peer *p) 
	if (atomic_read(&p->refcnt) == 1) {

		struct inet_peer **stack[PEER_MAXDEPTH];

		struct inet_peer ***stackptr, ***delp;

		if (lookup(p->v4daddr) != p)

		if (lookup(p->v4daddr, stack) != p)

			BUG();

		delp = stackptr - 1; /* *delp[0] == p */

		if (p->avl_left == peer_avl_empty) {
@@ -373,7 +379,7 @@ struct inet_peer *inet_getpeer(__be32 daddr, int create) 


	/* Look up for the address quickly. */

	read_lock_bh(&peer_pool_lock);

	p = lookup(daddr);

	p = lookup(daddr, NULL);

	if (p != peer_avl_empty)

		atomic_inc(&p->refcnt);

	read_unlock_bh(&peer_pool_lock);
@@ -400,7 +406,7 @@ struct inet_peer *inet_getpeer(__be32 daddr, int create) 


	write_lock_bh(&peer_pool_lock);

	/* Check if an entry has suddenly appeared. */

	p = lookup(daddr);

	p = lookup(daddr, stack);

	if (p != peer_avl_empty)

		goto out_free;

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