Debug And System Messages; Exec And Virtual Exec Processes - Cisco uBR10012 Troubleshooting Manual

Chapter 3 Troubleshooting PRE-1 Modules
CPUHOG Errors
The router displays a %SYS-3-CPUHOG error message when a process is using an excessive amount of
processor cycles. For example, using the logging buffered command to allocate a significant amount of
memory (for example, 200 MB) for log buffers could generate a %SYS-3-CPUHOG message, because
allocating such an amount of memory requires a large amount of processor time.
For more information on what could cause this problem and how to resolve it, see the document What
Causes %SYS-3-CPUHOG Messages, at the following URL:
http://www.cisco.com/en/US/products/sw/iosswrel/ps1831/products_tech_note09186a00800a6ac4.sht
ml

Debug and System Messages

A large volume of debugging messages or system messages can take a significant amount of processor
time, because the PRE-1 module must spend a significant amount of time displaying these messages on
the console port. In particular, this can happen when using the verbose or detail mode of a debug
command, or if the debug command is dumping the contents of packets or packet buffers.
Use the following techniques to reduce the number of these messages:
1.
2.
3.

Exec and Virtual Exec Processes

The Exec process is the Cisco IOS process that handles the TTY serial lines (console, auxiliary,
asynchronous), and the Virtual Exec process handles the Virtual TTY (VTY) Telnet sessions. These
processes run as mid-level processes, so if either one is exceptionally busy, it could generate a high CPU
usage level.
OL-1237-01
Turn off the debugging messages by entering the no debug all command in privileged EXEC mode:
Router# no debug all
All possible debugging has been turned off
Router#
Disable console messages by using the no logging console command in global configuration mode:
Router# configure terminal
Router(config)# no logging console
Router(config)#
To keep the logging of console messages, but to limit the number of messages that can be displayed,
use the logging rate-limit command. You can rate-limit all messages (including debug messages),
or just the console messages, using one of the following commands:
Router(config)# logging rate-limit console number-of-messages-per-second
Router(config)# logging rate-limit all number-of-messages-per-second
If you have logged into the router using a Telnet connection, you can disable debug messages using
the terminal default monitor command in privileged EXEC mode:
Router# terminal default monitor
Router#
Cisco uBR10012 Universal Broadband Router Troubleshooting Guide
Troubleshooting Common System Problems
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