diff options
| -rw-r--r-- | ChangeLog | 1 | ||||
| -rw-r--r-- | TODO | 5 | ||||
| -rw-r--r-- | src/cache.c | 15 |
3 files changed, 15 insertions, 6 deletions
@@ -24,6 +24,7 @@ o Now default synchronization mode is ftfw instead of alarm o rename `examples' directory to `doc' o add support for related conntracks (requires Linux kernel >= 2.6.22) o show error and warning messages to stderr +o hash lookup speedups based on comments from netdev's discussions version 0.9.5 (2007/07/29) ------------------------------ @@ -11,9 +11,10 @@ by dificulty levels: [X] ignorepool with unlimited size and ignore networks [ ] selective conntracks removal [ ] debian/rpm packages - [ ] improve website - [ ] Dumazet improvement hashtable (multiply vs. divide) + [X] improve website + [X] Dumazet improvement hashtable (multiply vs. divide) [X] add secmark support + [ ] logging support for the statistics mode = Requires some work = [ ] study better keepalived transitions diff --git a/src/cache.c b/src/cache.c index 80cde01..b92957a 100644 --- a/src/cache.c +++ b/src/cache.c @@ -38,7 +38,14 @@ static u_int32_t hash(const void *data, struct hashtable *table) ((nfct_get_attr_u16(ct, ATTR_ORIG_PORT_SRC) << 16) | (nfct_get_attr_u16(ct, ATTR_ORIG_PORT_DST)))); - return jhash_2words(a, b, 0) % table->hashsize; + /* + * Instead of returning hash % table->hashsize (implying a divide) + * we return the high 32 bits of the (hash * table->hashsize) that will + * give results between [0 and hashsize-1] and same hash distribution, + * but using a multiply, less expensive than a divide. See: + * http://www.mail-archive.com/netdev@vger.kernel.org/msg56623.html + */ + return ((u_int64_t)jhash_2words(a, b, 0) * table->hashsize) >> 32; } static u_int32_t hash6(const void *data, struct hashtable *table) @@ -47,15 +54,15 @@ static u_int32_t hash6(const void *data, struct hashtable *table) const struct us_conntrack *u = data; struct nf_conntrack *ct = u->ct; - a = jhash(nfct_get_attr(ct, ATTR_ORIG_IPV6_SRC), sizeof(u_int32_t), + a = jhash(nfct_get_attr(ct, ATTR_ORIG_IPV6_SRC), sizeof(u_int32_t)*4, ((nfct_get_attr_u8(ct, ATTR_ORIG_L3PROTO) << 16) | (nfct_get_attr_u8(ct, ATTR_ORIG_L4PROTO)))); - b = jhash(nfct_get_attr(ct, ATTR_ORIG_IPV6_DST), sizeof(u_int32_t), + b = jhash(nfct_get_attr(ct, ATTR_ORIG_IPV6_DST), sizeof(u_int32_t)*4, ((nfct_get_attr_u16(ct, ATTR_ORIG_PORT_SRC) << 16) | (nfct_get_attr_u16(ct, ATTR_ORIG_PORT_DST)))); - return jhash_2words(a, b, 0) % table->hashsize; + return ((u_int64_t)jhash_2words(a, b, 0) * table->hashsize) >> 32; } static int __compare(const struct nf_conntrack *ct1, |