[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: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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43e683926f
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243bbcaa09
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@ -87,10 +87,12 @@ static DEFINE_RWLOCK(peer_pool_lock);
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static int peer_total;
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/* Exported for sysctl_net_ipv4. */
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int inet_peer_threshold = 65536 + 128; /* start to throw entries more
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int inet_peer_threshold __read_mostly = 65536 + 128; /* start to throw entries more
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* aggressively at this stage */
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int inet_peer_minttl = 120 * HZ; /* TTL under high load: 120 sec */
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int inet_peer_maxttl = 10 * 60 * HZ; /* usual time to live: 10 min */
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int inet_peer_minttl __read_mostly = 120 * HZ; /* TTL under high load: 120 sec */
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int inet_peer_maxttl __read_mostly = 10 * 60 * HZ; /* usual time to live: 10 min */
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int inet_peer_gc_mintime __read_mostly = 10 * HZ;
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int inet_peer_gc_maxtime __read_mostly = 120 * HZ;
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static struct inet_peer *inet_peer_unused_head;
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static struct inet_peer **inet_peer_unused_tailp = &inet_peer_unused_head;
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@ -99,9 +101,6 @@ static DEFINE_SPINLOCK(inet_peer_unused_lock);
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static void peer_check_expire(unsigned long dummy);
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static DEFINE_TIMER(peer_periodic_timer, peer_check_expire, 0, 0);
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/* Exported for sysctl_net_ipv4. */
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int inet_peer_gc_mintime = 10 * HZ,
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inet_peer_gc_maxtime = 120 * HZ;
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/* Called from ip_output.c:ip_init */
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void __init inet_initpeers(void)
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@ -151,20 +150,27 @@ static void unlink_from_unused(struct inet_peer *p)
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spin_unlock_bh(&inet_peer_unused_lock);
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}
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/* Called with local BH disabled and the pool lock held. */
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#define lookup(daddr) \
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/*
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* Called with local BH disabled and the pool lock held.
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* _stack is known to be NULL or not at compile time,
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* so compiler will optimize the if (_stack) tests.
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*/
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#define lookup(_daddr,_stack) \
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({ \
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struct inet_peer *u, **v; \
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stackptr = stack; \
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*stackptr++ = &peer_root; \
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if (_stack) { \
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stackptr = _stack; \
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*stackptr++ = &peer_root; \
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} \
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for (u = peer_root; u != peer_avl_empty; ) { \
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if (daddr == u->v4daddr) \
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if (_daddr == u->v4daddr) \
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break; \
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if ((__force __u32)daddr < (__force __u32)u->v4daddr) \
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if ((__force __u32)_daddr < (__force __u32)u->v4daddr) \
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v = &u->avl_left; \
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else \
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v = &u->avl_right; \
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*stackptr++ = v; \
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if (_stack) \
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*stackptr++ = v; \
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u = *v; \
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} \
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u; \
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@ -288,7 +294,7 @@ static void unlink_from_pool(struct inet_peer *p)
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if (atomic_read(&p->refcnt) == 1) {
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struct inet_peer **stack[PEER_MAXDEPTH];
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struct inet_peer ***stackptr, ***delp;
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if (lookup(p->v4daddr) != p)
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if (lookup(p->v4daddr, stack) != p)
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BUG();
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delp = stackptr - 1; /* *delp[0] == p */
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if (p->avl_left == peer_avl_empty) {
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@ -373,7 +379,7 @@ struct inet_peer *inet_getpeer(__be32 daddr, int create)
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/* Look up for the address quickly. */
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read_lock_bh(&peer_pool_lock);
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p = lookup(daddr);
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p = lookup(daddr, NULL);
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if (p != peer_avl_empty)
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atomic_inc(&p->refcnt);
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read_unlock_bh(&peer_pool_lock);
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@ -400,7 +406,7 @@ struct inet_peer *inet_getpeer(__be32 daddr, int create)
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write_lock_bh(&peer_pool_lock);
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/* Check if an entry has suddenly appeared. */
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p = lookup(daddr);
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p = lookup(daddr, stack);
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if (p != peer_avl_empty)
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goto out_free;
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