Cisco CRS-1 - Carrier Routing System Router Troubleshooting Manual page 181

Process Monitoring and Troubleshooting
This chapter includes the following sections:
System Manager, page 8-172
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Watchdog System Monitor, page 8-172
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• Core Dumps, page 8-173
follow Command, page 8-173
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• show processes Commands, page 8-175
Redundancy and Process Restartability, page 8-179
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Process States, page 8-180
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Process Monitoring, page 8-182
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Monitoring CPU Usage and Using Syslog Messages, page 8-183
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Troubleshooting High CPU Utilization and Process Timeouts, page 8-185
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Troubleshooting a Process Restart, page 8-195
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The Cisco IOS XR software is built on a modular system of processes. A process is a group of threads
that share virtual address (memory) space. Each process provides specific functionality for the system
and runs in a protected memory space to ensure that problems with one process cannot impact the entire
system. Multiple instances of a process can run on a single node, and multiple threads of execution can
run on each process instance.
Threads are units of execution, each with an execution context that includes a stack and registers. A
thread is in effect a "sub-process" managed by the parent, responsible for executing a subportion of the
overall process. For example, Open Shortest Path First (OSPF) has a thread which handles "hello"
receipt and transmission. A thread may only run when the parent process is allocate runtime by the
system scheduler. A process with threads is a multi-threaded process.
Under normal operating conditions, processes are managed automatically by the
Cisco IOS XR software. Processes are started, stopped, or restarted as required by the running
configuration of the router. In addition, processes are checkpointed to optimize performance during
process restart and automatic switchover. For more information on processes, see Cisco IOS XR System
Management Configuration Guide for the Cisco CRS-1 Router.
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Cisco IOS XR Troubleshooting Guide for the Cisco CRS-1 Router
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