The %SYS-3-CPUHOG: Task ran for [dec] msec ([dec]/[dec]), process = [chars], PC = [hex] message is received when a process runs for too long, and does not relinquish the processor. The process is a "CPU hog".
Each process should run only for a small amount of time before relinquishing the processor, so that other processes can run. This problem can be caused by many conditions such as traffic, system load, hardware, operational configuration, a configuration change, initialization of many interfaces, a high momentary error rate, or a sustained abnormal condition.
If this message appears during startup or during OIR of a card, no action is required.
If this message appears during an attempt to access a Flash memory device, replace the affected Flash memory device.
If this message occurs during normal router operation, the cause is most probably a software failure. To take advantage of recent fixes, upgrade your system to the latest Cisco IOS Software Release in the release train.
If the error message indicates a Spanning Tree Protocol (STP) process, try to:
Reduce the number of VLANs (through VLAN Trunking Protocol (VTP) transparent).
Add an allowed VLAN list to all trunks. The switch will not send out a bridge protocol data unit (BPDU) for VLANs that are disallowed on the trunks. This is called pruning (especially for IP phones).
Remove packets per second of outgoing traffic from every port.
Reduce the load on the CPU from the STP Queue Handler process.
Greatly reduce the amount of memory permanently allocated by STP.
Greatly reduce the amount of memory transiently allocated by STP in order to transmit BPDUs.