[c-nsp] 7206VXR Big CPU Increase After 12.4 Upgrade

[Rodney Dunn]

Hank,

I researched this for you and talked with the TAC SR owner.

This performance hit is due to new packet classification mechanism
that went in to 12.4(11)T.

They are working to bring the performance back inline with the previous
classification code. The only problem apparently is that it will be
the next release of T as the changes are too large and complex to put
in the throttle.

I've asked them for some more clarification on what they are doing.

I'll pass it on when I get it.

Rodney



On Wed, Mar 21, 2007 at 08:59:58AM +0200, Hank Nussbacher wrote:
> Oldish thread:
> 
> >Re: 7206VXR Big CPU Increase After 12.4 Upgrade
> >
> >For the benefit of the list and archives, we went back to 12.3.22 yesterday
> >and our CPU levels dropped back to more like the previous levels.
> >
> >The "%IF-4-BACKWARD_COUNTERS" have also disappeared since we went back to
> >12.3.
> >
> >Would recommend staying with 12.3 if you don't need a specific feature of
> >12.4 as it is slightly more resource hungry (around 15 percent higher at
> >just over 200Mbps in our experience).
> >
> >Thanks to everyone for their assistance,
> >Mark.
> 
> Mark,
> 
> We hit the same problem (CPU doubled - see graph from mid-Feb at - 
> http://noc.ilan.net.il/stats/ILAN-CPU/tau-7206-cpu.html) going from 
> 12.4(4)T1 to 12.4(11)T1 so if you want try 12.4(4)T1  and your CPU should 
> not rise.   We have an open TAC case on this issue for 3 weeks now.
> 
> -Hank Nussbacher
> http://www.interall.co.il
> 
> 
> >----- Original Message -----
> >From: "Rodney Dunn" <rodunn[at]cisco.com>
> >To: "Mark Taylor" <maillist[at]smashie.ision.co.uk>
> >Cc: <cisco-nsp[at]puck.nether.net>
> >Sent: Tuesday, January 30, 2007 4:02 PM
> >Subject: Re: [c-nsp] 7206VXR Big CPU Increase After 12.4 Upgrade
> >
> >
> > > There are a lot of new features in the switching vectors between
> > > 12.3 and 12.4 so you will see an increase in CPU.
> > >
> > > In an upcoming 12.4(last)T release that will then be 12.5 mainline
> > > that is being changed so the net result will not be the same
> > > CPU impact as features are enabled that has traditionally been the
> > > case.
> > >
> > > Can you post your configuration minus any senstive information in it?
> > >
> > > Or unicast it to me...
> > >
> > > Rodney
> > >
> > > On Tue, Jan 30, 2007 at 02:01:39PM -0000, Mark Taylor wrote:
> > >> Hi,
> > >>
> > >> We upgraded one of our 7206VXR NPE-G1's from 12.3(12a) to 12.4(12) this
> > >> morning to cover the recent security releases. We decided to make the
> > >> major
> > >> revision jump as we were reloading.
> > >>
> > >> After the reload the box jumped from 20 percent cpu to 35 percent on the
> > >> new
> > >> 12.4(12) image and at the time there was around 75Mbps in each direction
> > >> of
> > >> traffic running through the box - so an immediate increase of 15 percent.
> > >>
> > >> Now there is about 185Mbps each way and cpu is at 65 percent. This would
> > >> have been about 45 percent before the change of image, so an increase of
> > >> 20
> > >> percent.
> > >>
> > >> This is looking very much like cpu could potentially increase more
> > >> quickly
> > >> than traffic. The jump in cpu between images is beginning to concern me a
> > >> little. Has anybody else experienced this? Is it normal?
> > >>
> > >> The box is a peering router running IPv4 and OSPF, a full BGP table from
> > >> one
> > >> upstream and about 20 other direct peers at a small IX and a few ACLs.
> > >> CEF
> > >> is still running.
> > >>
> > >> I was hoping to get around 350Mbps through the box before running out of
> > >> cpu
> > >> and it was looking that way based on 12.3(12a). I guess I could go back
> > >> to
> > >> 12.3(22) which is fixed, assuming that the increase in cpu comes with
> > >> 12.4.
> > >> I just wanted to find out if this big jump in cpu between releases was
> > >> normal/expected.
> > >>
> > >> Any help/experience appreciated.
> > >> Thanks,
> > >> Mark.
> > >>
> 
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