CPU utilization query
Experts,
Core-Switch#sh processes cpu so 1
CPU utilization for five seconds: 40%/1%; one minute: 35%; five minutes: 35%
PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process
30 5248799482118370040 247 19.51% 16.34% 16.71% 0 Cat4k Mgmt LoPri
29 20503967322395826272 0 12.95% 12.54% 12.48% 0 Cat4k Mgmt HiPri
52 424438104 753203851 563 2.79% 2.51% 2.48% 0 Spanning Tree
58 339416368 752979472 450 0.87% 0.68% 0.65% 0 IP Input
18 105731420 236879115 446 1.19% 0.59% 0.54% 0 ARP Input
119 30336808 296249983 102 0.31% 0.28% 0.29% 0 HSRP (Standby)
136 456 595 766 0.23% 0.25% 0.11% 1 SSH Process
117 25561340 4205501 6078 0.95% 0.22% 0.06% 0 SpanTree Flush
73 25176580 74544113 337 0.15% 0.17% 0.15% 0 CEF: IPv4 proces
5 77307312 7631624 10129 0.00% 0.13% 0.16% 0 Check heaps
60 8963520 120836284 74 0.07% 0.12% 0.11% 0 CDP Protocol
102 4048480 648058463 6 0.07% 0.07% 0.07% 0 PM Callback
28 18581940 1187792 15644 0.00% 0.04% 0.00% 0 Per-minute Jobs
40 2467048 11026359 223 0.07% 0.04% 0.05% 0 Compute load avg
27 6981148 48482600 143 0.00% 0.04% 0.05% 0 Per-Second Jobs
123 28174196 16539707 1703 0.00% 0.04% 0.05% 0 SNMP ENGINE
53 2513132 87421476 28 0.00% 0.02% 0.00% 0 DTP Protocol
Can you please help me understand this results.
What is CPU utilization for five seconds: 40%/1%?
Comments
Hi Krishna,
It's CPU utilization percent for the last five seconds. The second number is CPU interrupt percent.
According to Cisco documentation, its normal for the interrupt percentage to be greater than 0 percent and less than 5 percent. It is acceptable for the interrupt percentage to be between 5 percent and 10 percent. An interrupt percentage over 10 percent should be investigated.
Hope this helps!
40%, tells how busy the CPU was in the past 5 seconds. This number is the total CPU utilization for all the active system processes, including the percentage of time at the interrupt level.
1%, shows the percentage of time at the interrupt level in the past 5 seconds. The interrupt percentage is the CPU time spent receiving packets from the switch hardware. The percentage of time at interrupt level is always less than or equal to the total CPU utilization.
http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/troubleshooting/cpu_util.html
What others have left out is the magic 39%: the device spent 39% of CPU handling packets via CEF (i.e. non-interrupt-based packet forwarding). I got this result by calculating 40% - 1% = 39%, if it wasn't otherwise obvious.
Hi Peety,
If CEF is non-interrupt-based packet forwarding, then what is interrupt-based packet forwarding?
Legacy packet forwarding, which includes "process switching" (every inbound packet requires the router to "walk" the routing table to find the best match) and "fast-cache switching" (every inbound packet checks the routing cache for recent matches; if one is found, it's used, otherwise the router "walks" the routing table to find a match AND populates the routing cache with that information; cache entries are aged out after five minutes).
Prcoess switching is one of them.
EDIT
Peety has given better explanation.