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Troubleshooting High CPU on 1841

Hi All,

I am trying to troubleshoot high CPU usage on an 1841. It has a five minute average (as you can see below) of 37% CPU usage, not no process has a CPU usage that high, so how can this be? An invisible process is tying up the CPU? This router typically has a sustained CPU of 4-5%, now its circa 40%.

Any ideas people can give to diagnose this would be greatly appreciated

1841#show processes cpu sorted

CPU utilization for five seconds: 47%/44%; one minute: 42%; five minutes: 37%

PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process

  63     2455548    828599       2963  1.30%  1.43%  1.34%   0 IP Input        

196      946308  19241151         49  0.81%  0.90%  0.94%   0 IP SLA Mon Event

203      364616   2545972        143  0.24%  0.20%  0.21%   0 PPP manager     

204      254988   2546391        100  0.16%  0.14%  0.15%   0 PPP Events      

  54       99092     66335       1493  0.16%  0.09%  0.08%   0 DSL State Machin

110       11132     83074        134  0.08%  0.00%  0.00%   0 RUDPV1 Main Proc

   2       29676     16674       1779  0.08%  0.02%  0.00%   0 Load Meter      

126       94244    815990        115  0.08%  0.04%  0.06%   0 RBSCP Background

  52       94880     65786       1442  0.08%  0.09%  0.08%   0 DSL State Machin

  47        5104     16844        303  0.08%  0.00%  0.00%   0 ATM Periodic    

198       36060    172104        209  0.08%  0.03%  0.01%   0 IP NAT Ager     

215         636        85       7482  0.08%  0.14%  0.06% 195 SSH Process     

  73       36544    325090        112  0.08%  0.01%  0.00%   0 SSS Feature Time

  13           0         1          0  0.00%  0.00%  0.00%   0 AAA_SERVER_DEADT

  12           0         5          0  0.00%  0.00%  0.00%   0 AAA high-capacit

  14           0         1          0  0.00%  0.00%  0.00%   0 Policy Manager  

  11           4         2       2000  0.00%  0.00%  0.00%   0 ATM Idle Timer  

  18        6560     24952        262  0.00%  0.00%  0.00%   0 HC Counter Timer

  15        2136      5055        422  0.00%  0.00%  0.00%   0 DDR Timers      

  16           4         2       2000  0.00%  0.00%  0.00%   0 Entity MIB API  

  21           0         2          0  0.00%  0.00%  0.00%   0 SMART           

  17         124       479        258  0.00%  0.00%  0.00%   0 EEM ED Syslog   

  23           0         2          0  0.00%  0.00%  0.00%   0 Dialer event    

  19           0         2          0  0.00%  0.00%  0.00%   0 Serial Backgroun

  25           0         2          0  0.00%  0.00%  0.00%   0 XML Proxy Client

  26         564        77       7324  0.00%  0.05%  0.03% 194 SSH Process     

  27           0         1          0  0.00%  0.00%  0.00%   0 Inode Table Dest

  10       96164    133931        718  0.00%  0.04%  0.05%   0 ARP Input

1841#show processes memory sorted

Processor Pool Total:  187088432 Used:   25946504 Free:  161141928

      I/O Pool Total:   28311552 Used:    4829408 Free:   23482144

PID TTY  Allocated      Freed    Holding    Getbufs    Retbufs Process

   0   0   41699136   11015608   24831508          0          0 *Init*         

  39   0     654496       1272     635224          0          0 USB Startup    

   0   0          0          0     396868          0          0 *MallocLite*   

  26 194     668188     305088     355188          0          0 SSH Process    

   0   0   82213740   85010240     327468     384284       4680 *Dead*         

206   0    5649108  226327924     304828     240700          0 DNS Server     

  17   0     256856          0     266828     113400          0 EEM ED Syslog  

   5   0    1124620    1508800     261576     660112     841924 Pool Manager   

   1   0     541068     319832     228208          0          0 Chunk Manager  

208   0  228498968    6552940     193324      12924      37700 DNS Server Input

201   0     175812        196     182652          0          0 PPPoE Background

204   0     474392     402664     135540          0          0 PPP Events     

145   0     116528        496     125004          0          0 Crypto WUI     

  29   0     134284        184     100436          0          0 Net Background 

152   0     666584     611404      80544          0          0 Crypto ACL     

  84   0      66676          0      76648          0          0 IP RIB Update  

  87   0      73552          0      73552          0          0 CEF process    

   3   0     629332      43544      59636          0          0 Dynamic DNS Upda

215 195    1564748    1515020      44248          0          0 SSH Process    

221 196     813376     720008      43636          0          0 SSH Process    

195   0      40556        196      39380          0          0 DHCPD Receive  

159   0      24912          0      37884          0          0 Crypto Delete Ma

193   0      14216      27956      29036          0          0 VTEMPLATE Backgr

202   0     158520      12996      25996          0          0 PPPoE Discovery

147   0        284          0      25256          0          0 RPMS_PROC_MAIN 

192   0        196          0      25168          0          0 tHUB

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Super Bronze

Troubleshooting High CPU on 1841

Disclaimer


The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

jwbensley wrote:

Hi All,

I am trying to troubleshoot high CPU usage on an 1841. It has a five minute average (as you can see below) of 37% CPU usage, not no process has a CPU usage that high, so how can this be? An invisible process is tying up the CPU? This router typically has a sustained CPU of 4-5%, now its circa 40%.

Any ideas people can give to diagnose this would be greatly appreciated

That appears to be mostly interrupt CPU, which ought to be fast path packet forwarding.

What's you overall interface loading when this is happening?

5 REPLIES
Super Bronze

Troubleshooting High CPU on 1841

Disclaimer


The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

jwbensley wrote:

Hi All,

I am trying to troubleshoot high CPU usage on an 1841. It has a five minute average (as you can see below) of 37% CPU usage, not no process has a CPU usage that high, so how can this be? An invisible process is tying up the CPU? This router typically has a sustained CPU of 4-5%, now its circa 40%.

Any ideas people can give to diagnose this would be greatly appreciated

That appears to be mostly interrupt CPU, which ought to be fast path packet forwarding.

What's you overall interface loading when this is happening?

Troubleshooting High CPU on 1841

Use CPU profiling to determine where the CPU spends its time when it increased by interrupts. You will need cisco to decode  output.

http://www.cisco.com/en/US/products/hw/routers/ps359/products_tech_note09186a00801c2af0.shtml

New Member

Troubleshooting High CPU on 1841

Of course, interrupt processing, mental slip I think!

Although the router was only pushing around 5Mbps of traffic (in one interface and out the other, and it only has these two Ethernet interfaces. There are 2 WIC-1ADSL cards which weren't doing anything, a few Kbps or bps).

Due to the wonders of CEF shouldn't CPU processing only occur for control packets like ICMP, or BGP and IGP updates etc. Despite the low traffic volume, do you think (as a side question) the type of traffic passing through was causing the high CPU load as apposed to the volume of traffic?

Many thanks,

James.

Super Bronze

Troubleshooting High CPU on 1841

Disclaimer


The    Author of this posting offers the information contained within this    posting without consideration and with the reader's understanding that    there's no implied or expressed suitability or fitness for any  purpose.   Information provided is for informational purposes only and  should not   be construed as rendering professional advice of any kind.  Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In    no event shall Author be liable for any damages whatsoever  (including,   without limitation, damages for loss of use, data or  profit) arising  out  of the use or inability to use the posting's  information even if  Author  has been advised of the possibility of such  damage.

Posting

CEF is just an optimal fast path routing lookup, still uses CPU, and I believe it would be in the "interrupt" category.

The 1841 is rated at 75 Kpps (fast path), so 5 Mbps duplex shouldn't need much more than about 25% CPU, but much depends on your traffic characteristics and router configuration.

New Member

Troubleshooting High CPU on 1841

Great, thanks for the info!

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