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IP6 FIB: Micro optimization in lookup

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The mask is increasingly small.
This saves a few cycles and becomes significant when there are many
prefix lengths.

Change-Id: Ibd0c9331f675697bb4e90e8ad617994f83edec9c
Signed-off-by: Pierre Pfister <ppfister@cisco.com>
This commit is contained in:
Pierre Pfister
2016-04-08 17:49:48 +01:00
committed by Gerrit Code Review
parent c42552d4e0
commit b3e80947dc
1 changed files with 9 additions and 4 deletions
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13
vnet/vnet/ip/ip6_forward.c
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@ -64,19 +64,24 @@ ip6_fib_lookup_with_table (ip6_main_t * im, u32 fib_index, ip6_address_t * dst)
int i, len;
int rv;
BVT(clib_bihash_kv) kv, value;
u64 fib;
len = vec_len (im->prefix_lengths_in_search_order);
kv.key[0] = dst->as_u64[0];
kv.key[1] = dst->as_u64[1];
fib = ((u64)((fib_index))<<32);
for (i = 0; i < len; i++)
{
int dst_address_length = im->prefix_lengths_in_search_order[i];
ip6_address_t * mask = &im->fib_masks[dst_address_length];
ASSERT(dst_address_length >= 0 && dst_address_length <= 128);
kv.key[0] = dst->as_u64[0] & mask->as_u64[0];
kv.key[1] = dst->as_u64[1] & mask->as_u64[1];
kv.key[2] = ((u64)((fib_index))<<32) | dst_address_length;
//As lengths are decreasing, masks are increasingly specific.
kv.key[0] &= mask->as_u64[0];
kv.key[1] &= mask->as_u64[1];
kv.key[2] = fib | dst_address_length;
rv = BV(clib_bihash_search_inline_2)(&im->ip6_lookup_table, &kv, &value);
if (rv == 0)