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There are around 500+ ipv6 and ~500 ipv4 networks in "neutron
net-list".Almost all are same ipv6 subnets  .

I will try to recreate this with small number of ipv6 subnet in a different
setup.

On Wed, Nov 18, 2015 at 9:04 PM, Sridhar Gaddam <sgaddam at redhat.com> wrote:

>
>
> On 11/18/2015 08:28 PM, Brian Haley wrote:
>
>> On 11/18/2015 07:33 AM, kevin parrikar wrote:
>>
>>> i am trying Juno *without *DVR and there are around 500 sub nets in each
>>> network
>>> node.
>>>
>>> Network nodes have 500+ dnsmasq process which are configured to give
>>> ipv6,ipv4
>>> addresses out of this some fluctuates between D and S state while others
>>> are in
>>> continuous S state.Probably because of too many processes in D state with
>>> "rtnetlink_rcv" in "wchan" its showing very high load average.
>>>
>>>
>>> functions in stack when in D state:
>>>
>>> [<ffffffff816360a9>] rtnetlink_rcv+0x19/0x30
>>> [<ffffffff81653e25>] netlink_unicast+0xd5/0x1b0
>>> [<ffffffff8165420e>] netlink_sendmsg+0x30e/0x680
>>> [<ffffffff8160e32b>] sock_sendmsg+0x8b/0xc0
>>> [<ffffffff8160e871>] SYSC_sendto+0x121/0x1c0
>>> [<ffffffff8160f25e>] SyS_sendto+0xe/0x10
>>> [<ffffffff817342dd>] system_call_fastpath+0x1a/0x1f
>>> [<ffffffffffffffff>] 0xffffffffffffffff
>>>
>>> but in couple of seconds it changes to S state with this in stack,all
>>> idle
>>> process have this in stack.
>>>
>>> [<ffffffff811d20d9>] poll_schedule_timeout+0x49/0x70
>>> [<ffffffff811d2ac6>] do_select+0x5b6/0x780
>>> [<ffffffff811d2e5c>] core_sys_select+0x1cc/0x2e0
>>> [<ffffffff811d301b>] SyS_select+0xab/0x100
>>> [<ffffffff817342dd>] system_call_fastpath+0x1a/0x1f
>>> [<ffffffffffffffff>] 0xffffffffffffffff
>>>
>>> interface in which dnsmasq is listening has " tentative dadfailed" in
>>> "scope
>>> global" for ipv6 for all the dnsmasq process that are in D state.
>>>
>>> i don't understand why duplicate ipv6 issue is coming when there are
>>> vlan tags
>>> to separate each sub net.For ipv4 duplicate IP issue is not coming for
>>> same subnet.
>>>
>>
>> DAD failure is fatal for the address, as it won't be tried again without
>> bouncing the interface or tweaking the disable_ipv6 sysctl on the
>> interface. The "tentative" flag is just showing it is still in that state
>> (i.e. waiting for DAD to complete).  Figuring out why this is happening
>> will most likely solve your problem, but there isn't enough here to go on.
>>
>> The fact that you don't see an IPv4 'duplicate' message is that it's not
>> going to typically do it, so you could have a duplicate there and just not
>> know it.
>>
>> I'd say to try Kilo or Liberty, but it's unclear if this is a Neutron
>> issue or something more basic with your setup.
>>
>> Agree with Brian.
> Is the problem seen even with a single (or say two) IPv6 subnets? Or is it
> seen only at scale?
>
> -Brian
>>
>>
>> Not able to understand why dnsmasq that are connected to interfaces that
>>> have
>>> "tentative dadfailed " continuously changes between S and D state while
>>> others
>>> are idle.
>>>
>>> attached is the strace while dnsmasq is in D state.
>>>
>>> Any idea about this issue?
>>>
>>>
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>>
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>
>
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