How Can the Exec and Virtual Exec Processes Cause High
CPU Utilization?
If there is a lot of data transferred through these sessions, the CPU utilization for the Exec process increases.
This is because when the router wants to send a simple character through these lines, the router uses some
CPU resources:
For the console (Exec), the router uses one interrupt per character.
The console interrupt can be seen in the show stacks command output:
router#show stacks
Minimum process stacks:
Free/Size Name
11516/12000 Router Init
9404/12000 Init
5520/6000 AIM_MIB_CREATION
5448/6000 RADIUS INITCONFIG
9728/12000 Virtual Exec
Interrupt level stacks:
Level Called Unused/Size Name
1 23035463 7008/9000 Network interfaces
2 0 9000/9000 Timebase Reference Interrupt
3 0 9000/9000 PA Management Int Handler
6 9791 8892/9000 16552 Con/Aux Interrupt
7 1334963882 8920/9000 MPC860 TIMER INTERRUPT
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For the vty line (Virtual Exec), the telnet session has to build a TCP packet and send the character(s)
to the telnet client.
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Troubleshoot High CPU Utilization in the Exec Process
Listed here are some possible reasons for high CPU utilization in the Exec process:
Too much data is sent through the console port.
Too many console messages generated by the router is a possible cause.
Check to see if any debugs have been started on the router with the show debugging
command.
1.
2. Disable console logging on the router with (no logging console ).
Verify if a long output is printed on the console (for example, a show tech−support or a
show memory ).
3.
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There is a bug in the Cisco IOS software.
Use the Bug Toolkit ( registered customers only) to look for bugs with this symptom in your Cisco IOS
software release.
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· The exec command is configured for asynchronous and auxiliary lines.
