[Dnsmasq-discuss] dnsmasq process in S, D state causing high load average

green krypton greenkrypton93 at gmail.com
Wed Feb 17 12:53:14 GMT 2016


500 instances in 500 vlans

On Sat, Nov 21, 2015 at 3:05 AM, Simon Kelley <simon at thekelleys.org.uk>
wrote:

> On 18/11/15 12:23, green krypton wrote:
> > I have around 500 dnsmasq process which are configured to give ipv6,ipv4
> > addresses out of this some fluctuate 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" error for ipv6 .
> >
> > 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?
> >
> >
>
> Dnsmasq polls every second whilst one or more interfaces it's listening
> on are still doing DAD. Once all interfaces have completed DAD,it stops
> polling.
>
>
> Are you really running 500 separate instances on dnsmasq? That's an
> installation which is way out of the normal way of doing things.
>
>
> Cheers,
>
> Simon.
>
> >
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> >
>
>
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