On Mon, 2 Apr 2007 11:43:19 +1000 CaT <cat@zip.com.au> wrote:

quoted text
> I take minute by minute snapshots of network traffic by sampling
> /proc/net/dev and most of the time everything works fine. Occasionally
> though I get petabyte byte traffic and corresponding packet traffic.

How frequently?

Are you able to provide some actual numbers (expected and actual values),
so we can look at the bit patterns?

quoted text
> This happens on an AMD64, dual core smp box with Broadcom NetXtreme II
> nics.

What driver drivers that?  b44.c?

quoted text
> The issue happens with both nics but at different times. The same
> sampling code runs on p4 boxes with ht on and e1000 nics without issues
> so I don't believe it's an issue with my code (famous last words :)
> which just does an re to extract the data on a per-line basis and prints
> it out. Still, I'll be adding code to log any big readings and hopefully
> it'll happen again sooner rather then later.
> 
> There is no preemption involved and the kernel is a monolythic build of
> 2.6.19.[12] (there are two servers).

We do perform racy 64-bit updates of some of the stats counters.  But
that'll only affect 32-bit kernels and I'm assuming you're running a 64-bit
kernel on that AMD64 box (are you?)

Plus it's odd that both the byte-counters and the packet-counters go wonky
at the same time.

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