High CPU utilization caused by virtual-exec

Unanswered Question
Feb 29th, 2008

I observed that packet drop happened whenever CPU utilization spike occurred, the reason caused CPU spike is due to virtual-exec. Could you please advertise what's the solution for this kind of problem?

Feb 29 04:45:30: %SYS-1-CPURISINGTHRESHOLD: Threshold: Total CPU Utilization(Total/Intr): 84%/0%, Top 3 processes(Pid/Util): 187/82%, 166/0%, 118/0%

ITT0001R#sh process cpu | i 187

187 5404 54285 99 4.63% 0.56% 0.53% 66 Virtual Exec

ITT0001R#

Thank You!

I have this problem too.
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lamav Fri, 02/29/2008 - 06:34

Hi:

I had this exact same problem on a switch years ago. I opened a TAC case and it turned out to be a bug in the code.

Now, I dont remember the eswitch or version of IOS, since it was so long ago, but the upgrade was definitely the fix.

HTH

Victor

trinawong Fri, 02/29/2008 - 06:54

I am suspecting that there is backup configuration everyday that cause this CPU spikes.

marikakis Fri, 02/29/2008 - 07:20

Hello,

That could be it. If you manage to associate the issue with a particular hour every day, then you are in the way of resolving it. Please note, that high CPU util from e.g. TFTP normally (unless a bug exists) doesn't cause real issues on the router. I mean, the router can handle those paced procedures and if there is something better to do (such as forwarding normal traffic), the router will do it. Your pings and traces however might fail and give you false alarms. If you want to check this further to confirm whether a real problem in your network exists or not, try sending test traffic that will go through the router instead of targeting the router itself. Did you have any complaints from users about bad performance?

Kind Regards,

M.

trinawong Fri, 02/29/2008 - 15:55

Thanks for your reply!

We are observing voice R-factor alarm come out during that particular time, there is no complain from end user so far regarding voice since it always happen at midnight, just would like to fix this issue, not sure if upgrade IOS would be a solution?

Thank You,

marikakis Sat, 03/01/2008 - 03:33

Hello,

Please forgive my ignorance on voice terminology. From what I have quickly read this R-factor alarm is based on loss, delay and echo. The big question is how are those performance metrics actually measured. I mean, if the application that gives you the alarm is based on ping-style measurements, then what I have already said about potential false alarms in a previous post still holds to some extent. I say "some extent" because it depends on whether the probe packets go through the router.

No complaints from end users is a sad situation. Complaints can stress you, but you do not wonder if issue is real. You just know it. :-)

I am afraid I belong to the conservative school of network troubleshooting thought. I won't change my router, my IOS, my wardrobe with all my clothes to solve an issue, unless there is a good reason to do so and there is enough evidence that action will resolve the confirmed issue. The good thing with this approach is that it gets you right in most cases, but you might once in a while lose. I cannot tell you to change your IOS. I do not have enough evidence regarding your issue. As a consequence, I do not know of an IOS that will fix it. Perhaps you could move to the latest version of the train you are already using, if this procedure is not a problem for you.

Kind Regards,

M.

p.s. Make sure you find out exactly what those applications that do the backup are doing to your router. This will give you more clues about your case and could help you find a proper IOS if required.

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