Why is my router CPU at 40% when no processes use more than 2%?

Solution 1:

The figures shown by a "show processes cpu" are a little misleading, in your output below:

lev1841#show processes cpu sorted 
CPU utilization for five seconds: 41%/39%; one minute: 42%; five minutes: 32%

The five seconds figure of 41%/39% should be read as "Total CPU usage"/"CPU Usage Caused by traffic".

i.e. Your processes are using 2%, the rest is being caused by the normal flow of traffic through the router. If you were to shut down the traffic carrying interfaces, this figure would drop away to around 2%.

It might be worth checking that you've enable CEF on the router?

Solution 2:

One thing to try:

router(config)#no logging console

no logging console will disable the output of the debug message on the serial console. As the console is interrupt-driven, each character is an interrupt.

Solution 3:

Have you looked at the Cisco troubleshooting guide for high cpu ? It has an extensive guide on what to do when encountering high CPU loads.

Included are :

Determining Causes and Solving the Problem :

• High CPU Utilization due to Interrupts

• High CPU when Enabling Netflow NDE on Cisco 7600 Series Router

• High CPU Utilization due to Processes

• PCI and FAST Memory Pools Show Very High Utilization

• %SNMP-4-HIGHCPU: Process exceeds [dec]ms threshold ([dec]ms IOS quantum) for [chars] of [chars]--result [chars]

• High CPU due to Software Encryption