inetpeer: various changes
Try to reduce cache line contentions in peer management, to reduce IP defragmentation overhead. - peer_fake_node is marked 'const' to make sure its not modified. (tested with CONFIG_DEBUG_RODATA=y) - Group variables in two structures to reduce number of dirtied cache lines. One named "peers" for avl tree root, its number of entries, and associated lock. (candidate for RCU conversion) - A second one named "unused_peers" for unused list and its lock - Add a !list_empty() test in unlink_from_unused() to avoid taking lock when entry is not unused. - Use atomic_dec_and_lock() in inet_putpeer() to avoid taking lock in some cases. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
David S. Miller
Родитель
6b10de38f0
Коммит
d6cc1d642d
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@ -70,17 +70,25 @@
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static struct kmem_cache *peer_cachep __read_mostly;
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#define node_height(x) x->avl_height
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static struct inet_peer peer_fake_node = {
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.avl_left = &peer_fake_node,
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.avl_right = &peer_fake_node,
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#define peer_avl_empty ((struct inet_peer *)&peer_fake_node)
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static const struct inet_peer peer_fake_node = {
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.avl_left = peer_avl_empty,
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.avl_right = peer_avl_empty,
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.avl_height = 0
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};
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#define peer_avl_empty (&peer_fake_node)
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static struct inet_peer *peer_root = peer_avl_empty;
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static DEFINE_RWLOCK(peer_pool_lock);
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static struct {
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struct inet_peer *root;
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rwlock_t lock;
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int total;
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} peers = {
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.root = peer_avl_empty,
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.lock = __RW_LOCK_UNLOCKED(peers.lock),
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.total = 0,
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};
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#define PEER_MAXDEPTH 40 /* sufficient for about 2^27 nodes */
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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 __read_mostly = 65536 + 128; /* start to throw entries more
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* aggressively at this stage */
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@ -89,8 +97,13 @@ 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 LIST_HEAD(unused_peers);
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static DEFINE_SPINLOCK(inet_peer_unused_lock);
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static struct {
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struct list_head list;
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spinlock_t lock;
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} unused_peers = {
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.list = LIST_HEAD_INIT(unused_peers.list),
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.lock = __SPIN_LOCK_UNLOCKED(unused_peers.lock),
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};
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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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@ -131,9 +144,11 @@ void __init inet_initpeers(void)
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/* Called with or without local BH being disabled. */
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static void unlink_from_unused(struct inet_peer *p)
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{
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spin_lock_bh(&inet_peer_unused_lock);
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list_del_init(&p->unused);
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spin_unlock_bh(&inet_peer_unused_lock);
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if (!list_empty(&p->unused)) {
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spin_lock_bh(&unused_peers.lock);
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list_del_init(&p->unused);
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spin_unlock_bh(&unused_peers.lock);
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}
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}
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/*
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@ -146,9 +161,9 @@ static void unlink_from_unused(struct inet_peer *p)
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struct inet_peer *u, **v; \
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if (_stack != NULL) { \
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stackptr = _stack; \
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*stackptr++ = &peer_root; \
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*stackptr++ = &peers.root; \
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} \
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for (u = peer_root; u != peer_avl_empty; ) { \
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for (u = peers.root; u != peer_avl_empty; ) { \
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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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@ -262,7 +277,7 @@ do { \
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n->avl_right = peer_avl_empty; \
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**--stackptr = n; \
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peer_avl_rebalance(stack, stackptr); \
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} while(0)
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} while (0)
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/* May be called with local BH enabled. */
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static void unlink_from_pool(struct inet_peer *p)
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@ -271,7 +286,7 @@ static void unlink_from_pool(struct inet_peer *p)
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do_free = 0;
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write_lock_bh(&peer_pool_lock);
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write_lock_bh(&peers.lock);
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/* Check the reference counter. It was artificially incremented by 1
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* in cleanup() function to prevent sudden disappearing. If the
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* reference count is still 1 then the node is referenced only as `p'
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@ -303,10 +318,10 @@ static void unlink_from_pool(struct inet_peer *p)
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delp[1] = &t->avl_left; /* was &p->avl_left */
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}
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peer_avl_rebalance(stack, stackptr);
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peer_total--;
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peers.total--;
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do_free = 1;
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}
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write_unlock_bh(&peer_pool_lock);
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write_unlock_bh(&peers.lock);
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if (do_free)
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kmem_cache_free(peer_cachep, p);
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@ -326,16 +341,16 @@ static int cleanup_once(unsigned long ttl)
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struct inet_peer *p = NULL;
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/* Remove the first entry from the list of unused nodes. */
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spin_lock_bh(&inet_peer_unused_lock);
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if (!list_empty(&unused_peers)) {
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spin_lock_bh(&unused_peers.lock);
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if (!list_empty(&unused_peers.list)) {
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__u32 delta;
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p = list_first_entry(&unused_peers, struct inet_peer, unused);
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p = list_first_entry(&unused_peers.list, struct inet_peer, unused);
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delta = (__u32)jiffies - p->dtime;
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if (delta < ttl) {
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/* Do not prune fresh entries. */
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spin_unlock_bh(&inet_peer_unused_lock);
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spin_unlock_bh(&unused_peers.lock);
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return -1;
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}
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@ -345,7 +360,7 @@ static int cleanup_once(unsigned long ttl)
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* before unlink_from_pool() call. */
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atomic_inc(&p->refcnt);
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}
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spin_unlock_bh(&inet_peer_unused_lock);
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spin_unlock_bh(&unused_peers.lock);
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if (p == NULL)
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/* It means that the total number of USED entries has
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@ -364,11 +379,11 @@ struct inet_peer *inet_getpeer(__be32 daddr, int create)
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struct inet_peer **stack[PEER_MAXDEPTH], ***stackptr;
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/* Look up for the address quickly. */
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read_lock_bh(&peer_pool_lock);
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read_lock_bh(&peers.lock);
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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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read_unlock_bh(&peers.lock);
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if (p != peer_avl_empty) {
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/* The existing node has been found. */
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@ -390,7 +405,7 @@ struct inet_peer *inet_getpeer(__be32 daddr, int create)
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atomic_set(&n->ip_id_count, secure_ip_id(daddr));
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n->tcp_ts_stamp = 0;
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write_lock_bh(&peer_pool_lock);
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write_lock_bh(&peers.lock);
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/* Check if an entry has suddenly appeared. */
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p = lookup(daddr, stack);
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if (p != peer_avl_empty)
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@ -399,10 +414,10 @@ struct inet_peer *inet_getpeer(__be32 daddr, int create)
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/* Link the node. */
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link_to_pool(n);
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INIT_LIST_HEAD(&n->unused);
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peer_total++;
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write_unlock_bh(&peer_pool_lock);
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peers.total++;
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write_unlock_bh(&peers.lock);
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if (peer_total >= inet_peer_threshold)
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if (peers.total >= inet_peer_threshold)
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/* Remove one less-recently-used entry. */
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cleanup_once(0);
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@ -411,7 +426,7 @@ struct inet_peer *inet_getpeer(__be32 daddr, int create)
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out_free:
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/* The appropriate node is already in the pool. */
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atomic_inc(&p->refcnt);
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write_unlock_bh(&peer_pool_lock);
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write_unlock_bh(&peers.lock);
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/* Remove the entry from unused list if it was there. */
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unlink_from_unused(p);
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/* Free preallocated the preallocated node. */
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@ -425,12 +440,12 @@ static void peer_check_expire(unsigned long dummy)
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unsigned long now = jiffies;
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int ttl;
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if (peer_total >= inet_peer_threshold)
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if (peers.total >= inet_peer_threshold)
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ttl = inet_peer_minttl;
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else
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ttl = inet_peer_maxttl
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- (inet_peer_maxttl - inet_peer_minttl) / HZ *
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peer_total / inet_peer_threshold * HZ;
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peers.total / inet_peer_threshold * HZ;
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while (!cleanup_once(ttl)) {
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if (jiffies != now)
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break;
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@ -439,22 +454,25 @@ static void peer_check_expire(unsigned long dummy)
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/* Trigger the timer after inet_peer_gc_mintime .. inet_peer_gc_maxtime
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* interval depending on the total number of entries (more entries,
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* less interval). */
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if (peer_total >= inet_peer_threshold)
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if (peers.total >= inet_peer_threshold)
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peer_periodic_timer.expires = jiffies + inet_peer_gc_mintime;
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else
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peer_periodic_timer.expires = jiffies
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+ inet_peer_gc_maxtime
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- (inet_peer_gc_maxtime - inet_peer_gc_mintime) / HZ *
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peer_total / inet_peer_threshold * HZ;
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peers.total / inet_peer_threshold * HZ;
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add_timer(&peer_periodic_timer);
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}
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void inet_putpeer(struct inet_peer *p)
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{
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spin_lock_bh(&inet_peer_unused_lock);
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if (atomic_dec_and_test(&p->refcnt)) {
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list_add_tail(&p->unused, &unused_peers);
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local_bh_disable();
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if (atomic_dec_and_lock(&p->refcnt, &unused_peers.lock)) {
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list_add_tail(&p->unused, &unused_peers.list);
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p->dtime = (__u32)jiffies;
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spin_unlock(&unused_peers.lock);
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}
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spin_unlock_bh(&inet_peer_unused_lock);
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local_bh_enable();
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}
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