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authorEric Dumazet <eric.dumazet@gmail.com>2010-06-14 15:35:21 -0400
committerDavid S. Miller <davem@davemloft.net>2010-06-15 02:13:08 -0400
commitd6cc1d642de9284cb26488ea390d915b50ee2504 (patch)
tree7652471f541c11f63f54e282a04a9cba614e8d5e /net/ipv4/inetpeer.c
parent6b10de38f0ef4e921a1f6e5cba2b6c92d6b46ecd (diff)
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>
Diffstat (limited to 'net/ipv4/inetpeer.c')
-rw-r--r--net/ipv4/inetpeer.c94
1 files changed, 56 insertions, 38 deletions
diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c
index 6bcfe52a9c87..035673fd42d4 100644
--- a/net/ipv4/inetpeer.c
+++ b/net/ipv4/inetpeer.c
@@ -70,17 +70,25 @@
70static struct kmem_cache *peer_cachep __read_mostly; 70static struct kmem_cache *peer_cachep __read_mostly;
71 71
72#define node_height(x) x->avl_height 72#define node_height(x) x->avl_height
73static struct inet_peer peer_fake_node = { 73
74 .avl_left = &peer_fake_node, 74#define peer_avl_empty ((struct inet_peer *)&peer_fake_node)
75 .avl_right = &peer_fake_node, 75static const struct inet_peer peer_fake_node = {
76 .avl_left = peer_avl_empty,
77 .avl_right = peer_avl_empty,
76 .avl_height = 0 78 .avl_height = 0
77}; 79};
78#define peer_avl_empty (&peer_fake_node) 80
79static struct inet_peer *peer_root = peer_avl_empty; 81static struct {
80static DEFINE_RWLOCK(peer_pool_lock); 82 struct inet_peer *root;
83 rwlock_t lock;
84 int total;
85} peers = {
86 .root = peer_avl_empty,
87 .lock = __RW_LOCK_UNLOCKED(peers.lock),
88 .total = 0,
89};
81#define PEER_MAXDEPTH 40 /* sufficient for about 2^27 nodes */ 90#define PEER_MAXDEPTH 40 /* sufficient for about 2^27 nodes */
82 91
83static int peer_total;
84/* Exported for sysctl_net_ipv4. */ 92/* Exported for sysctl_net_ipv4. */
85int inet_peer_threshold __read_mostly = 65536 + 128; /* start to throw entries more 93int inet_peer_threshold __read_mostly = 65536 + 128; /* start to throw entries more
86 * aggressively at this stage */ 94 * aggressively at this stage */
@@ -89,8 +97,13 @@ int inet_peer_maxttl __read_mostly = 10 * 60 * HZ; /* usual time to live: 10 min
89int inet_peer_gc_mintime __read_mostly = 10 * HZ; 97int inet_peer_gc_mintime __read_mostly = 10 * HZ;
90int inet_peer_gc_maxtime __read_mostly = 120 * HZ; 98int inet_peer_gc_maxtime __read_mostly = 120 * HZ;
91 99
92static LIST_HEAD(unused_peers); 100static struct {
93static DEFINE_SPINLOCK(inet_peer_unused_lock); 101 struct list_head list;
102 spinlock_t lock;
103} unused_peers = {
104 .list = LIST_HEAD_INIT(unused_peers.list),
105 .lock = __SPIN_LOCK_UNLOCKED(unused_peers.lock),
106};
94 107
95static void peer_check_expire(unsigned long dummy); 108static void peer_check_expire(unsigned long dummy);
96static DEFINE_TIMER(peer_periodic_timer, peer_check_expire, 0, 0); 109static DEFINE_TIMER(peer_periodic_timer, peer_check_expire, 0, 0);
@@ -131,9 +144,11 @@ void __init inet_initpeers(void)
131/* Called with or without local BH being disabled. */ 144/* Called with or without local BH being disabled. */
132static void unlink_from_unused(struct inet_peer *p) 145static void unlink_from_unused(struct inet_peer *p)
133{ 146{
134 spin_lock_bh(&inet_peer_unused_lock); 147 if (!list_empty(&p->unused)) {
135 list_del_init(&p->unused); 148 spin_lock_bh(&unused_peers.lock);
136 spin_unlock_bh(&inet_peer_unused_lock); 149 list_del_init(&p->unused);
150 spin_unlock_bh(&unused_peers.lock);
151 }
137} 152}
138 153
139/* 154/*
@@ -146,9 +161,9 @@ static void unlink_from_unused(struct inet_peer *p)
146 struct inet_peer *u, **v; \ 161 struct inet_peer *u, **v; \
147 if (_stack != NULL) { \ 162 if (_stack != NULL) { \
148 stackptr = _stack; \ 163 stackptr = _stack; \
149 *stackptr++ = &peer_root; \ 164 *stackptr++ = &peers.root; \
150 } \ 165 } \
151 for (u = peer_root; u != peer_avl_empty; ) { \ 166 for (u = peers.root; u != peer_avl_empty; ) { \
152 if (_daddr == u->v4daddr) \ 167 if (_daddr == u->v4daddr) \
153 break; \ 168 break; \
154 if ((__force __u32)_daddr < (__force __u32)u->v4daddr) \ 169 if ((__force __u32)_daddr < (__force __u32)u->v4daddr) \
@@ -262,7 +277,7 @@ do { \
262 n->avl_right = peer_avl_empty; \ 277 n->avl_right = peer_avl_empty; \
263 **--stackptr = n; \ 278 **--stackptr = n; \
264 peer_avl_rebalance(stack, stackptr); \ 279 peer_avl_rebalance(stack, stackptr); \
265} while(0) 280} while (0)
266 281
267/* May be called with local BH enabled. */ 282/* May be called with local BH enabled. */
268static void unlink_from_pool(struct inet_peer *p) 283static void unlink_from_pool(struct inet_peer *p)
@@ -271,7 +286,7 @@ static void unlink_from_pool(struct inet_peer *p)
271 286
272 do_free = 0; 287 do_free = 0;
273 288
274 write_lock_bh(&peer_pool_lock); 289 write_lock_bh(&peers.lock);
275 /* Check the reference counter. It was artificially incremented by 1 290 /* Check the reference counter. It was artificially incremented by 1
276 * in cleanup() function to prevent sudden disappearing. If the 291 * in cleanup() function to prevent sudden disappearing. If the
277 * reference count is still 1 then the node is referenced only as `p' 292 * reference count is still 1 then the node is referenced only as `p'
@@ -303,10 +318,10 @@ static void unlink_from_pool(struct inet_peer *p)
303 delp[1] = &t->avl_left; /* was &p->avl_left */ 318 delp[1] = &t->avl_left; /* was &p->avl_left */
304 } 319 }
305 peer_avl_rebalance(stack, stackptr); 320 peer_avl_rebalance(stack, stackptr);
306 peer_total--; 321 peers.total--;
307 do_free = 1; 322 do_free = 1;
308 } 323 }
309 write_unlock_bh(&peer_pool_lock); 324 write_unlock_bh(&peers.lock);
310 325
311 if (do_free) 326 if (do_free)
312 kmem_cache_free(peer_cachep, p); 327 kmem_cache_free(peer_cachep, p);
@@ -326,16 +341,16 @@ static int cleanup_once(unsigned long ttl)
326 struct inet_peer *p = NULL; 341 struct inet_peer *p = NULL;
327 342
328 /* Remove the first entry from the list of unused nodes. */ 343 /* Remove the first entry from the list of unused nodes. */
329 spin_lock_bh(&inet_peer_unused_lock); 344 spin_lock_bh(&unused_peers.lock);
330 if (!list_empty(&unused_peers)) { 345 if (!list_empty(&unused_peers.list)) {
331 __u32 delta; 346 __u32 delta;
332 347
333 p = list_first_entry(&unused_peers, struct inet_peer, unused); 348 p = list_first_entry(&unused_peers.list, struct inet_peer, unused);
334 delta = (__u32)jiffies - p->dtime; 349 delta = (__u32)jiffies - p->dtime;
335 350
336 if (delta < ttl) { 351 if (delta < ttl) {
337 /* Do not prune fresh entries. */ 352 /* Do not prune fresh entries. */
338 spin_unlock_bh(&inet_peer_unused_lock); 353 spin_unlock_bh(&unused_peers.lock);
339 return -1; 354 return -1;
340 } 355 }
341 356
@@ -345,7 +360,7 @@ static int cleanup_once(unsigned long ttl)
345 * before unlink_from_pool() call. */ 360 * before unlink_from_pool() call. */
346 atomic_inc(&p->refcnt); 361 atomic_inc(&p->refcnt);
347 } 362 }
348 spin_unlock_bh(&inet_peer_unused_lock); 363 spin_unlock_bh(&unused_peers.lock);
349 364
350 if (p == NULL) 365 if (p == NULL)
351 /* It means that the total number of USED entries has 366 /* It means that the total number of USED entries has
@@ -364,11 +379,11 @@ struct inet_peer *inet_getpeer(__be32 daddr, int create)
364 struct inet_peer **stack[PEER_MAXDEPTH], ***stackptr; 379 struct inet_peer **stack[PEER_MAXDEPTH], ***stackptr;
365 380
366 /* Look up for the address quickly. */ 381 /* Look up for the address quickly. */
367 read_lock_bh(&peer_pool_lock); 382 read_lock_bh(&peers.lock);
368 p = lookup(daddr, NULL); 383 p = lookup(daddr, NULL);
369 if (p != peer_avl_empty) 384 if (p != peer_avl_empty)
370 atomic_inc(&p->refcnt); 385 atomic_inc(&p->refcnt);
371 read_unlock_bh(&peer_pool_lock); 386 read_unlock_bh(&peers.lock);
372 387
373 if (p != peer_avl_empty) { 388 if (p != peer_avl_empty) {
374 /* The existing node has been found. */ 389 /* The existing node has been found. */
@@ -390,7 +405,7 @@ struct inet_peer *inet_getpeer(__be32 daddr, int create)
390 atomic_set(&n->ip_id_count, secure_ip_id(daddr)); 405 atomic_set(&n->ip_id_count, secure_ip_id(daddr));
391 n->tcp_ts_stamp = 0; 406 n->tcp_ts_stamp = 0;
392 407
393 write_lock_bh(&peer_pool_lock); 408 write_lock_bh(&peers.lock);
394 /* Check if an entry has suddenly appeared. */ 409 /* Check if an entry has suddenly appeared. */
395 p = lookup(daddr, stack); 410 p = lookup(daddr, stack);
396 if (p != peer_avl_empty) 411 if (p != peer_avl_empty)
@@ -399,10 +414,10 @@ struct inet_peer *inet_getpeer(__be32 daddr, int create)
399 /* Link the node. */ 414 /* Link the node. */
400 link_to_pool(n); 415 link_to_pool(n);
401 INIT_LIST_HEAD(&n->unused); 416 INIT_LIST_HEAD(&n->unused);
402 peer_total++; 417 peers.total++;
403 write_unlock_bh(&peer_pool_lock); 418 write_unlock_bh(&peers.lock);
404 419
405 if (peer_total >= inet_peer_threshold) 420 if (peers.total >= inet_peer_threshold)
406 /* Remove one less-recently-used entry. */ 421 /* Remove one less-recently-used entry. */
407 cleanup_once(0); 422 cleanup_once(0);
408 423
@@ -411,7 +426,7 @@ struct inet_peer *inet_getpeer(__be32 daddr, int create)
411out_free: 426out_free:
412 /* The appropriate node is already in the pool. */ 427 /* The appropriate node is already in the pool. */
413 atomic_inc(&p->refcnt); 428 atomic_inc(&p->refcnt);
414 write_unlock_bh(&peer_pool_lock); 429 write_unlock_bh(&peers.lock);
415 /* Remove the entry from unused list if it was there. */ 430 /* Remove the entry from unused list if it was there. */
416 unlink_from_unused(p); 431 unlink_from_unused(p);
417 /* Free preallocated the preallocated node. */ 432 /* Free preallocated the preallocated node. */
@@ -425,12 +440,12 @@ static void peer_check_expire(unsigned long dummy)
425 unsigned long now = jiffies; 440 unsigned long now = jiffies;
426 int ttl; 441 int ttl;
427 442
428 if (peer_total >= inet_peer_threshold) 443 if (peers.total >= inet_peer_threshold)
429 ttl = inet_peer_minttl; 444 ttl = inet_peer_minttl;
430 else 445 else
431 ttl = inet_peer_maxttl 446 ttl = inet_peer_maxttl
432 - (inet_peer_maxttl - inet_peer_minttl) / HZ * 447 - (inet_peer_maxttl - inet_peer_minttl) / HZ *
433 peer_total / inet_peer_threshold * HZ; 448 peers.total / inet_peer_threshold * HZ;
434 while (!cleanup_once(ttl)) { 449 while (!cleanup_once(ttl)) {
435 if (jiffies != now) 450 if (jiffies != now)
436 break; 451 break;
@@ -439,22 +454,25 @@ static void peer_check_expire(unsigned long dummy)
439 /* Trigger the timer after inet_peer_gc_mintime .. inet_peer_gc_maxtime 454 /* Trigger the timer after inet_peer_gc_mintime .. inet_peer_gc_maxtime
440 * interval depending on the total number of entries (more entries, 455 * interval depending on the total number of entries (more entries,
441 * less interval). */ 456 * less interval). */
442 if (peer_total >= inet_peer_threshold) 457 if (peers.total >= inet_peer_threshold)
443 peer_periodic_timer.expires = jiffies + inet_peer_gc_mintime; 458 peer_periodic_timer.expires = jiffies + inet_peer_gc_mintime;
444 else 459 else
445 peer_periodic_timer.expires = jiffies 460 peer_periodic_timer.expires = jiffies
446 + inet_peer_gc_maxtime 461 + inet_peer_gc_maxtime
447 - (inet_peer_gc_maxtime - inet_peer_gc_mintime) / HZ * 462 - (inet_peer_gc_maxtime - inet_peer_gc_mintime) / HZ *
448 peer_total / inet_peer_threshold * HZ; 463 peers.total / inet_peer_threshold * HZ;
449 add_timer(&peer_periodic_timer); 464 add_timer(&peer_periodic_timer);
450} 465}
451 466
452void inet_putpeer(struct inet_peer *p) 467void inet_putpeer(struct inet_peer *p)
453{ 468{
454 spin_lock_bh(&inet_peer_unused_lock); 469 local_bh_disable();
455 if (atomic_dec_and_test(&p->refcnt)) { 470
456 list_add_tail(&p->unused, &unused_peers); 471 if (atomic_dec_and_lock(&p->refcnt, &unused_peers.lock)) {
472 list_add_tail(&p->unused, &unused_peers.list);
457 p->dtime = (__u32)jiffies; 473 p->dtime = (__u32)jiffies;
474 spin_unlock(&unused_peers.lock);
458 } 475 }
459 spin_unlock_bh(&inet_peer_unused_lock); 476
477 local_bh_enable();
460} 478}