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CPU Utilisation does not addup to total CPU %

Hi, My 1760 router do have VPN hardware module, without it, CPU was high and encryption process too much of the CPU, now after we install VPN module, there is no cpu % for encryption process, but my question is sum of the CPU % is much much lower than the total CPU %, what are the hidden processes taking all these CPU

HHRTR01#sh proc cpu | ex 0.00
CPU utilization for five seconds: 15%/11%; one minute: 16%; five minutes: 18%
PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process
   5      145439      9297      15643  1.06%  0.22%  0.18%   0 Check heaps
  50        2312       473       4887  2.12%  0.56%  0.25%   6 SSH Process
  51       69168     50055       1381  0.24%  0.18%  0.19%   0 IP Input

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Accepted Solutions
Cisco Employee

Re: CPU Utilisation does not addup to total CPU %

Hi,

0.16%+0.57% = 0.73%

0.73% rounded = 1%

Total CPU utilization = 35%

CPU utilization under interrupt = 34%

CPU utilization in processes = 35%-34% = 1% = 0.73% rounded

You can't see what's happening under interrupt ('show stacks' gives you the amount of network/timer/... interrupts but it's not very useful).

Usually, what happens under interrupt is the traffic forwarding using CEF.

So, at first sight, there's nothing to worry about on your router. It's a bit busy forwarding packets.

If you need to troubleshoot the CPU utilization under interrupt, you will need to do profiling with the assistance of a TAC engineer who has the ability to decode the profiling results.

hope this helps,

X.

4 REPLIES
Cisco Employee

Re: CPU Utilisation does not addup to total CPU %

The 15% include the 11% of CPU usage under interrupt. The sum of 5-sec CPU usage of all processes should give you 15%-11%=4%.

Total CPU utilization = CPU utilization in processes + CPU utilization in interrupt.

X.

New Member

Re: CPU Utilisation does not addup to total CPU %

Hi, Thanks for reply but it doesnt make sense to me , look below 5sec total is less than 1%, any way how can I chk interupt CPU utilisation.

PHTHRTR01#sh proc cpu | ex 0.00
CPU utilization for five seconds: 35%/34%; one minute: 41%; five minutes: 36%
PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process
  51      126074     81191       1552  0.16%  0.28%  0.21%   0 IP Input
  54       11119      1667       6670  0.57%  4.19%  1.96%   6 SSH Process

New Member

Re: CPU Utilisation does not addup to total CPU %

Hi ,

Thank for reply,

But it dosn't make sense to me, 5sec total is less than 1% but total is above 30%, any way how could I chk interupt CPU utilisation,

This router having prblem with hanging when IPSec traffic or WAN link utilisation goes high

PHTHRTR01#sh proc cpu | ex 0.00
CPU utilization for five seconds: 35%/34%; one minute: 41%; five minutes: 36%
PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process
  51      126074     81191       1552  0.16%  0.28%  0.21%   0 IP Input
  54       11119      1667       6670  0.57%  4.19%  1.96%   6 SSH Process

Cisco Employee

Re: CPU Utilisation does not addup to total CPU %

Hi,

0.16%+0.57% = 0.73%

0.73% rounded = 1%

Total CPU utilization = 35%

CPU utilization under interrupt = 34%

CPU utilization in processes = 35%-34% = 1% = 0.73% rounded

You can't see what's happening under interrupt ('show stacks' gives you the amount of network/timer/... interrupts but it's not very useful).

Usually, what happens under interrupt is the traffic forwarding using CEF.

So, at first sight, there's nothing to worry about on your router. It's a bit busy forwarding packets.

If you need to troubleshoot the CPU utilization under interrupt, you will need to do profiling with the assistance of a TAC engineer who has the ability to decode the profiling results.

hope this helps,

X.

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