Packet loss every 30.999 seconds

[Jeremy Chadwick]

On Mon, Dec 17, 2007 at 12:21:43AM -0500, Mark Fullmer wrote:
> While trying to diagnose a packet loss problem in a RELENG_6 snapshot dated
> November 8, 2007 it looks like I've stumbled across a broken driver or
> kernel routine which stops interrupt processing long enough to severly
> degrade network performance every 30.99 seconds.
>
> Packets appear to make it as far as ether_input() then get lost.

Are you sure this isn't being caused by something the switch is doing,
such as MAC/ARP cache clearing or LACP?  I'm just speculating, but it
would be worthwhile to remove the switch from the picture (crossover
cable to the rescue).

I know that at least in the case of fxp(4) and em(4), Jack Vogel does
some through testing of throughput using a professional/high-end packet
generator (some piece of hardware, I forget the name...)

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