ipv6: Use hash-threshold instead of modulo-N
Now that each nexthop stores its region boundary in the multipath hash function's output space, we can use hash-threshold instead of modulo-N in multipath selection. This reduces the number of checks we need to perform during lookup, as dead and linkdown nexthops are assigned a negative region boundary. In addition, in contrast to modulo-N, only flows near region boundaries are affected when a nexthop is added or removed. Signed-off-by: Ido Schimmel <idosch@mellanox.com> Acked-by: David Ahern <dsahern@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -455,7 +455,6 @@ static struct rt6_info *rt6_multipath_select(struct rt6_info *match,
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int strict)
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int strict)
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{
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{
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struct rt6_info *sibling, *next_sibling;
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struct rt6_info *sibling, *next_sibling;
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int route_choosen;
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/* We might have already computed the hash for ICMPv6 errors. In such
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/* We might have already computed the hash for ICMPv6 errors. In such
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* case it will always be non-zero. Otherwise now is the time to do it.
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* case it will always be non-zero. Otherwise now is the time to do it.
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@ -463,28 +462,19 @@ static struct rt6_info *rt6_multipath_select(struct rt6_info *match,
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if (!fl6->mp_hash)
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if (!fl6->mp_hash)
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fl6->mp_hash = rt6_multipath_hash(fl6, NULL);
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fl6->mp_hash = rt6_multipath_hash(fl6, NULL);
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route_choosen = fl6->mp_hash % (match->rt6i_nsiblings + 1);
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if (fl6->mp_hash <= atomic_read(&match->rt6i_nh_upper_bound))
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/* Don't change the route, if route_choosen == 0
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return match;
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* (siblings does not include ourself)
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*/
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if (route_choosen)
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list_for_each_entry_safe(sibling, next_sibling,
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&match->rt6i_siblings, rt6i_siblings) {
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route_choosen--;
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if (route_choosen == 0) {
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struct inet6_dev *idev = sibling->rt6i_idev;
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if (sibling->rt6i_nh_flags & RTNH_F_DEAD)
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list_for_each_entry_safe(sibling, next_sibling, &match->rt6i_siblings,
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break;
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rt6i_siblings) {
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if (sibling->rt6i_nh_flags & RTNH_F_LINKDOWN &&
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if (fl6->mp_hash > atomic_read(&sibling->rt6i_nh_upper_bound))
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idev->cnf.ignore_routes_with_linkdown)
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continue;
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break;
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if (rt6_score_route(sibling, oif, strict) < 0)
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if (rt6_score_route(sibling, oif, strict) < 0)
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break;
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break;
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match = sibling;
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match = sibling;
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break;
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break;
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}
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}
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}
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return match;
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return match;
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}
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}
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