[c-nsp] high cpu usage due to interrupts

ulisses ulisses.alonso at rediris.es
Tue Feb 13 11:23:57 EST 2007


Hi!

On 2007-02-13 10:22:41, Rodney Dunn wrote:
> On Tue, Feb 13, 2007 at 04:07:49PM +0100, ulisses wrote:
[...]
> > If I scale this by 2 it becomes around 60000 pps, not a lot isn't it?
> 
> For that CPU it probably is.

I found a reference to rsp1 performance! independent one! :-)

http://www.cnaf.infn.it/~ferrari/tfng/ds/ciscotest/perf/car/baseline/fe-noCAR.html

> > it seems there is a lot of margin...
> > 
> > > The CPU level there is probably normal for that processor.
> > > 
> > > If your VIPs have enough memory you could 'ip cef distributed'.
> > 
> > 'ip cef distributed' is not an option completed by pressing the
> > key '?' (only accounting option is shown, anyway i have entered it
> > and the output of the "show ip interfaces | include switch" is 
> > the same output and the ratio of high cpu interrupts has not changed.
> 
> That code with that RP may not support it that far back.

ok, I will take into account too

> > What I find extrange is that all percentage of the cpu usage goes 
> > to interrupts:
> 
> That's good. That tells you it's doing all the work switching packets
> and not process work.

ok, this is very interesting

> > Addionally (I haven't mentioned previously) is that when multicast
> > comes in (around 10-15 Mbps) the cpu burns at 100%. But first 
> > I wanted to make clear that there is no problem with unicast traffic.
> 
> Oh yeah...that would burn it like a champ. Especially when you don't
> have mdfs (multicast distributed fastswitching) capability.

I have it enabled

> And make sure even at the RP level you have "ip mroute-cache" enabled.
> It used to not be on by default.

I will double check this, and will do some tests tomorrow

> I think you need a newer RSP and VIPs that have the memory to do
> dCEF/MDFS if you want to run those packet rates through a 75xx.

It would be great if Cisco had the data sheets online.

Thanks so much

	Ulisses

> > > > EB-LasPalmas1#show ip interface | include is up|switch
> > > > ATM0/0 is up, line protocol is up
> > > > ATM0/0.1 is up, line protocol is up
> > > >   IP fast switching is enabled
> > > >   IP fast switching on the same interface is disabled
> > > >   IP Flow switching is enabled
> > > >   IP CEF switching is enabled
> > > >   IP Flow switching turbo vector
> > > >   IP Flow CEF switching turbo vector
> > > >   IP multicast fast switching is enabled
> > > >   IP multicast distributed fast switching is disabled
> > > > FastEthernet1/0/0 is up, line protocol is up
> > > >   IP fast switching is enabled
> > > >   IP fast switching on the same interface is disabled
> > > >   IP Flow switching is enabled
> > > >   IP CEF switching is enabled
> > > >   IP Distributed switching is enabled
> > > >   IP Flow switching turbo vector
> > > >   IP Flow CEF switching turbo vector
> > > >   IP multicast fast switching is enabled
> > > >   IP multicast distributed fast switching is enabled
> > > > FastEthernet2/0/0 is up, line protocol is up
> > > >   IP fast switching is enabled
> > > >   IP fast switching on the same interface is disabled
> > > >   IP Flow switching is enabled
> > > >   IP CEF switching is enabled
> > > >   IP Distributed switching is enabled
> > > >   IP Flow switching turbo vector
> > > >   IP Flow CEF switching turbo vector
> > > >   IP multicast fast switching is enabled
> > > >   IP multicast distributed fast switching is enabled
> > > > FastEthernet3/0/0 is up, line protocol is up
> > > >   IP fast switching is enabled
> > > >   IP fast switching on the same interface is disabled
> > > >   IP Flow switching is enabled
> > > >   IP CEF switching is enabled
> > > >   IP Distributed switching is enabled
> > > >   IP Flow switching turbo vector
> > > >   IP Flow CEF switching turbo vector
> > > >   IP multicast fast switching is enabled
> > > >   IP multicast distributed fast switching is enabled
> > > > FastEthernet3/1/0 is up, line protocol is up
> > > >   IP fast switching is enabled
> > > >   IP fast switching on the same interface is disabled
> > > >   IP Flow switching is enabled
> > > >   IP CEF switching is enabled
> > > >   IP Distributed switching is enabled
> > > >   IP Flow switching turbo vector
> > > >   IP Flow CEF switching turbo vector
> > > >   IP multicast fast switching is enabled
> > > >   IP multicast distributed fast switching is enabled
> > > > 
> > > > -- 
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> > > > RedIRIS/Red.es              /_/  RedIRIS  /_/
> > > > Edificio Bronce                   __                   Tel:    + 34 912127625
> > > > Pza. Manuel Gómez Moreno, s/n    /_/             Urgencias:    + 34 629148201
> > > > E-28020 Madrid                                         Fax:    + 34 915568864
> > > > 
> > > > _________________ Spanish Academic & Research Network _______________________
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> > 
> > -- 
> > _______________________________     __    ___________________________________
> >                                    /_/
> > Network Operation Center     __            __          Email:  noc at rediris.es
> > RedIRIS/Red.es              /_/  RedIRIS  /_/
> > Edificio Bronce                   __                   Tel:    + 34 912127625
> > Pza. Manuel Gómez Moreno, s/n    /_/             Urgencias:    + 34 629148201
> > E-28020 Madrid                                         Fax:    + 34 915568864
> > 
> > _________________ Spanish Academic & Research Network _______________________
> 

-- 
_______________________________     __    ___________________________________
                                   /_/
Network Operation Center     __            __          Email:  noc at rediris.es
RedIRIS/Red.es              /_/  RedIRIS  /_/
Edificio Bronce                   __                   Tel:    + 34 912127625
Pza. Manuel Gómez Moreno, s/n    /_/             Urgencias:    + 34 629148201
E-28020 Madrid                                         Fax:    + 34 915568864

_________________ Spanish Academic & Research Network _______________________


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