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Stephen Hemminger a écrit : > On Thu, 12 Nov 2009 15:11:36 +0100 > Eric Dumazet <eric.dumazet@gmail.com> wrote: > >> When handling large number of netdevices, inet_dump_ifaddr() >> is very slow because it has O(N^2) complexity. >> >> Instead of scanning one single list, we can use the NETDEV_HASHENTRIES >> sub lists of the dev_index hash table, and RCU lookups. >> >> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> > > You might be able to make RCU critical section smaller by moving > it into loop. > Indeed. But we dump at most one skb (<= 8192 bytes ?), so rcu_read_lock holding time is small, unless we meet many netdevices without addresses. I wonder if its really common... Thanks [PATCH net-next-2.6] ipv4: speedup inet_dump_ifaddr() When handling large number of netdevices, inet_dump_ifaddr() is very slow because it has O(N2) complexity. Instead of scanning one single list, we can use the NETDEV_HASHENTRIES sub lists of the dev_index hash table, and RCU lookups. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Acked-by: Stephen Hemminger <shemminger@vyatta.com> Signed-off-by: David S. Miller <davem@davemloft.net>