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Message-ID: <20091112111218.0a561166@nehalam> Date: Thu, 12 Nov 2009 11:12:18 -0800 From: Stephen Hemminger <shemminger@...tta.com> To: Eric Dumazet <eric.dumazet@...il.com> Cc: "David S. Miller" <davem@...emloft.net>, Linux Netdev List <netdev@...r.kernel.org> Subject: Re: [PATCH net-next-2.6] ipv4: speedup inet_dump_ifaddr() On Thu, 12 Nov 2009 18:44:25 +0100 Eric Dumazet <eric.dumazet@...il.com> wrote: > Stephen Hemminger a écrit : > > On Thu, 12 Nov 2009 15:11:36 +0100 > > Eric Dumazet <eric.dumazet@...il.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@...il.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 One case where that might happen is: modprobe dummy numdummies=10000 But dummy device should really be added with netlink, not at boot time. -- -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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