igmp: hash a hash table to speedup ip_check_mc_rcu()

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After IP route cache removal, multicast applications using
a lot of multicast addresses hit a O(N) behavior in ip_check_mc_rcu()

Add a per in_device hash table to get faster lookup.

This hash table is created only if the number of items in mc_list is
above 4.

Reported-by: Shawn Bohrer <sbohrer@rgmadvisors.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Tested-by: Shawn Bohrer <sbohrer@rgmadvisors.com>
Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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This commit is contained in:

Eric Dumazet 2013-06-07 08:48:57 -07:00 • committed by David S. Miller

parent 64153ce0a7

commit e989707135

4 changed files with 77 additions and 3 deletions

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1

include/linux/igmp.h

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5

include/linux/inetdevice.h

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1

net/ipv4/devinet.c

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73

net/ipv4/igmp.c

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