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Message-ID: <4CD83752.1070501@candelatech.com> Date: Mon, 08 Nov 2010 09:45:54 -0800 From: Ben Greear <greearb@...delatech.com> To: Eric Dumazet <eric.dumazet@...il.com> CC: NetDev <netdev@...r.kernel.org>, linux-kernel <linux-kernel@...r.kernel.org>, Tejun Heo <tj@...nel.org> Subject: Re: OOM when adding ipv6 route: How to make available more per-cpu memory? On 11/08/2010 03:02 AM, Eric Dumazet wrote: > Le samedi 06 novembre 2010 à 10:08 -0700, Ben Greear a écrit : > >> At least I don't see any percpu dumps in dmesg. I vaguely remember >> someone posting some ipv6 address scalability patches some time back. >> I think they had to hack on /proc fs as well. I'll see if I can >> dig those up. >> >>> Make sure udev / hotplug is not the problem, if you create your devices >>> very fast. >> >> We can create the macvlans w/out problem, though I'm sure that could >> be sped up. The problem is when we try to add IPv6 addresses to >> them. > > I see. Did you check /proc/sys/net/ipv6/ tunables ? > > For example, I bet you need to make route/max_size a bigger value than > default (4096) > > Following is working for me > > echo 16384>/proc/sys/net/ipv6/route/max_size > modprobe dummy numdummies=2000 > for a in `seq 1 1999` > do > ip -6 add add 4444::444:$a/24 dev dummy$a > done > > ip -6 ro | wc -l > 6008 That helps. I'm getting all of the IP addrs set now, but having trouble with some of the default gateways (I have one routing table per interface). ./local/sbin/ip -6 route replace default via 2002:9:8::1 dev eth7#458 table 726 RTNETLINK answers: No buffer space available dmesg is full of this: [247106.294743] ipv6: Neighbour table overflow. A quick look in /proc didn't show a tunable for this, but I'll go grub through the code. As for the route/max_size, it would be nice to see some useful kernel message in dmesg when this hit. Just telling the user '-ENOMEM' is not at all sufficient to help them figure out the problem. For that matter, why is there such a limit anyway? IPv4 doesn't appear to have any such limit? Thanks, Ben -- Ben Greear <greearb@...delatech.com> Candela Technologies Inc http://www.candelatech.com -- 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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