[c-nsp] High interrupt load on 7507

[Rodney Dunn]

David,

I don't have a setup to test right now but dot1q should surely
be dCEF switched.

What type of vip2 do you have and how much memory on them?

Post a 'sh cef line', 'sh int stat' after you clear the counters
and let it run for 2 minutes.

'sh run' so we can see the features you have enabled on the ingress
egress interfaces.

if the RSP cpu is high you are punting the traffic for some reason.

Rodney

On Wed, Jun 21, 2006 at 09:58:52AM -0400, David Coulson wrote:
> I'm trying to figure out a few issues with our 7507s running 12.4(8),
> where the CPU usage for interrupting will hit >95%. For example, we had
> a 4Gb file transfer which occurred between a VLAN on a GEIP and a plain
> old 100meg Ethernet interface on a PA-FE-TX (on a VIP2). We got up to
> about 60mbit in data rate transfer before it peaked out and the RSP was
> spending all it's time interrupting. We didn't seem to be doing that
> many packets/sec (maybe 7-8k), so I guess I'm a little confused as to
> why interrupting was so high on the box. Is interrupt rate a factor of
> packets/sec (like you'd think it is), or do other variables come into play.
> 
> Does using dot1q cause the RSP4 to interrupt rather than dCEF switch the
> packet? I'd like to try to get CPU down on the boxes, and it doesn't
> appear like the VIP processors are loaded (They run 30% tops, if that)
> during these times when the RSP is going nuts. I need to figure out what
> the best way to keep the RSP out of the way of packets is to avoid these
> periods of excessive interrupting, but I can't get rid of the VLANs and
> the router is already running dCEF on whatever it can. Since CEF
> requires an interrupt hit, am I just hitting my limit on what my RSP4
> can do?
> 
> Is it time to look at something else to do my dot1q L3, or am I just
> missing something with my config?
> 
> David
> 
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