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[IPV4]: Optimize inet_getpeer()

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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: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2007-03-06 20:23:10 -08:00 committed by David S. Miller
parent 43e683926f
commit 243bbcaa09
1 changed files with 22 additions and 16 deletions
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38
net/ipv4/inetpeer.c
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@ -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)
@ -151,20 +150,27 @@ 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; \
*stackptr++ = &peer_root; \
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; \
*stackptr++ = v; \
if (_stack) \
*stackptr++ = v; \
u = *v; \
} \
u; \
@ -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;