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authorRobert Olsson <robert.olsson@its.uu.se>2005-10-04 16:01:58 -0400
committerDavid S. Miller <davem@davemloft.net>2005-10-04 16:01:58 -0400
commite6308be85afee685347fa3440bed10faaa5d6c1a (patch)
tree9cb766b5b66f700528722b2e92745a2a6dcc3288 /net/ipv4/fib_trie.c
parent87bf9c97b4b3af8dec7b2b79cdfe7bfc0a0a03b2 (diff)
[IPV4]: fib_trie root-node expansion
The patch below introduces special thresholds to keep root node in the trie large. This gives a flatter tree at the cost of a modest memory increase. Overall it seems to be gain and this was also proposed by one the authors of the paper in recent a seminar. Main table after loading 123 k routes. Aver depth: 3.30 Max depth: 9 Root-node size 12 bits Total size: 4044 kB With the patch: Aver depth: 2.78 Max depth: 8 Root-node size 15 bits Total size: 4150 kB An increase of 8-10% was seen in forwading performance for an rDoS attack. Signed-off-by: Robert Olsson <robert.olsson@its.uu.se> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/fib_trie.c')
-rw-r--r--net/ipv4/fib_trie.c23
1 files changed, 21 insertions, 2 deletions
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 50c0519cd70d..0093ea08c7f5 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -286,6 +286,8 @@ static inline void check_tnode(const struct tnode *tn)
286 286
287static int halve_threshold = 25; 287static int halve_threshold = 25;
288static int inflate_threshold = 50; 288static int inflate_threshold = 50;
289static int halve_threshold_root = 15;
290static int inflate_threshold_root = 25;
289 291
290 292
291static void __alias_free_mem(struct rcu_head *head) 293static void __alias_free_mem(struct rcu_head *head)
@@ -449,6 +451,8 @@ static struct node *resize(struct trie *t, struct tnode *tn)
449 int i; 451 int i;
450 int err = 0; 452 int err = 0;
451 struct tnode *old_tn; 453 struct tnode *old_tn;
454 int inflate_threshold_use;
455 int halve_threshold_use;
452 456
453 if (!tn) 457 if (!tn)
454 return NULL; 458 return NULL;
@@ -541,10 +545,17 @@ static struct node *resize(struct trie *t, struct tnode *tn)
541 545
542 check_tnode(tn); 546 check_tnode(tn);
543 547
548 /* Keep root node larger */
549
550 if(!tn->parent)
551 inflate_threshold_use = inflate_threshold_root;
552 else
553 inflate_threshold_use = inflate_threshold;
554
544 err = 0; 555 err = 0;
545 while ((tn->full_children > 0 && 556 while ((tn->full_children > 0 &&
546 50 * (tn->full_children + tnode_child_length(tn) - tn->empty_children) >= 557 50 * (tn->full_children + tnode_child_length(tn) - tn->empty_children) >=
547 inflate_threshold * tnode_child_length(tn))) { 558 inflate_threshold_use * tnode_child_length(tn))) {
548 559
549 old_tn = tn; 560 old_tn = tn;
550 tn = inflate(t, tn); 561 tn = inflate(t, tn);
@@ -564,10 +575,18 @@ static struct node *resize(struct trie *t, struct tnode *tn)
564 * node is above threshold. 575 * node is above threshold.
565 */ 576 */
566 577
578
579 /* Keep root node larger */
580
581 if(!tn->parent)
582 halve_threshold_use = halve_threshold_root;
583 else
584 halve_threshold_use = halve_threshold;
585
567 err = 0; 586 err = 0;
568 while (tn->bits > 1 && 587 while (tn->bits > 1 &&
569 100 * (tnode_child_length(tn) - tn->empty_children) < 588 100 * (tnode_child_length(tn) - tn->empty_children) <
570 halve_threshold * tnode_child_length(tn)) { 589 halve_threshold_use * tnode_child_length(tn)) {
571 590
572 old_tn = tn; 591 old_tn = tn;
573 tn = halve(t, tn); 592 tn = halve(t, tn);