serious packet routing issue causing ntpd high load?

[Jeremy Chadwick]

On Wed, Oct 05, 2011 at 01:27:18AM +0100, Steven Hartland wrote:
> ----- Original Message ----- From: "Steven Hartland"
> <killing at multiplay.co.uk>
> ..
> >This seems very much like the following pr which was fixed:-
> >"Remove a bogusly introduced rtalloc_ign() in rev. 1.335/SVN 178029,
> >generating an RTM_MISS for every IP packet forwarded making user space
> >routing daemons unhappy":-
> >http://www.freebsd.org/cgi/query-pr.cgi?pr=124540
> >
> >The box is doing no routing, its fairly basic install with
> >1 main IP on em0 + 1 alias + gw addres and 1 private ip on em1.
> >
> >Its running mysql and thats about it.
> >
> >Any ideas?
> 
> This may also be causing significantly higher than expected
> kernel time as well:-
> 0 root      161  -8    0     0K  2560K -       1  44:26 23.88% kernel
> 
> I've removed the alias on em0 and removed all addresses from em1
> leaving just 1 address on em1 + lo0 and still seeing the same
> thing.

I can't reproduce this on our 8.2-STABLE boxes.  Specifically the one
which is running ntpd that provides time syncing for local clients, as
well as gets its source times from stratum 1/2 servers:

$ uptime
 5:45PM  up 6 days,  2:13, 1 user, load averages: 0.00, 0.00, 0.00
$ uname -a
FreeBSD XXXXXXXXXXXXXXX 8.2-STABLE FreeBSD 8.2-STABLE #0: Wed Sep 28 15:07:58 PDT 2011 root at XXXXXXXXXXXXXXX:/usr/obj/usr/src/sys/X7SBI_RELENG_8_amd64  amd64

 1428 root        1  44    0 11900K  2860K select  0   0:17  0.00% /usr/sbin/ntpd -c /conf/ME/ntp.conf -p /var/run/ntpd.pid -f

And "route -n monitor" shows no anomalies here.

Maybe you should tcpdump to find out if there is a client or peer which
is constantly pounding ntpd for some reason, or if ntpd is constantly
nagging some peer?  Not sure.

-- 
| Jeremy Chadwick                                jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                   Mountain View, CA, US |
| Making life hard for others since 1977.               PGP 4BD6C0CB |