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| author |   Patrick McHardy <kaber@trash.net> | 2007-07-07 22:37:38 -0700 |
|---|---|---|
| committer |   David S. Miller <davem@sunset.davemloft.net> | 2007-07-10 22:18:15 -0700 |
| commit | 7ae7730fd6d98be1afe8ad9ea77813de607ec970 (patch) | |
| tree | cb0cebe96de34a5d6116e4f76377e6ef4ca43547 /net/netfilter | |
| parent | [NETFILTER]: nf_conntrack: mark helpers __read_mostly (diff) | |
| download | linux-dev-7ae7730fd6d98be1afe8ad9ea77813de607ec970.tar.xz linux-dev-7ae7730fd6d98be1afe8ad9ea77813de607ec970.zip | |
[NETFILTER]: nf_conntrack: early_drop improvement
When the maximum number of conntrack entries is reached and a new
one needs to be allocated, conntrack tries to drop an unassured
connection from the same hash bucket the new conntrack would hash
to. Since with a properly sized hash the average number of entries
per bucket is 1, the chances of actually finding one are not very
good. This patch makes it walk the hash until a minimum number of
8 entries are checked.
Based on patch by Vasily Averin <vvs@sw.ru>.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/netfilter')
| -rw-r--r-- | net/netfilter/nf_conntrack_core.c | 22 |
1 files changed, 15 insertions, 7 deletions
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index d1fc019760a1..472396dac05c 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -377,21 +377,30 @@ nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple, } EXPORT_SYMBOL_GPL(nf_conntrack_tuple_taken); +#define NF_CT_EVICTION_RANGE 8 + /* There's a small race here where we may free a just-assured connection. Too bad: we're in trouble anyway. */ -static int early_drop(struct hlist_head *chain) +static int early_drop(unsigned int hash) { /* Use oldest entry, which is roughly LRU */ struct nf_conntrack_tuple_hash *h; struct nf_conn *ct = NULL, *tmp; struct hlist_node *n; + unsigned int i, cnt = 0; int dropped = 0; read_lock_bh(&nf_conntrack_lock); - hlist_for_each_entry(h, n, chain, hnode) { - tmp = nf_ct_tuplehash_to_ctrack(h); - if (!test_bit(IPS_ASSURED_BIT, &tmp->status)) - ct = tmp; + for (i = 0; i < nf_conntrack_htable_size; i++) { + hlist_for_each_entry(h, n, &nf_conntrack_hash[hash], hnode) { + tmp = nf_ct_tuplehash_to_ctrack(h); + if (!test_bit(IPS_ASSURED_BIT, &tmp->status)) + ct = tmp; + cnt++; + } + if (ct || cnt >= NF_CT_EVICTION_RANGE) + break; + hash = (hash + 1) % nf_conntrack_htable_size; } if (ct) atomic_inc(&ct->ct_general.use); @@ -425,8 +434,7 @@ struct nf_conn *nf_conntrack_alloc(const struct nf_conntrack_tuple *orig, if (nf_conntrack_max && atomic_read(&nf_conntrack_count) > nf_conntrack_max) { unsigned int hash = hash_conntrack(orig); - /* Try dropping from this hash chain. */ - if (!early_drop(&nf_conntrack_hash[hash])) { + if (!early_drop(hash)) { atomic_dec(&nf_conntrack_count); if (net_ratelimit()) printk(KERN_WARNING |