0

This Ubuntu server is booted with CPU isolation isolcpus=0-7, so 8 cores from 16 are reserved and the only processes that use them are numbered as worker_0 - worker_7.

As can be see by top's per CPU utilization the usage IS measured properly for Cpu0 - Cpu7 so to take CPU6 & CPU7 as examples where they are only 18.9% & 35.7% idle respectively the relevant threads worker_6 & worker_7 just show 0.0% CPU usage.

I've tried updating top to the latest version, it didn't help... is this a known kernel bug maybe? I'm Using 3.16.0-71-generic on Ubuntu 14.04

top - 17:36:51 up 282 days,  3:51,  2 users,  load average: 5.93, 6.42, 6.39
Threads:  53 total,   8 running,  45 sleeping,   0 stopped,   0 zombie
%Cpu0  : 42.5 us,  1.4 sy,  0.0 ni, 56.1 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu1  : 51.3 us,  1.1 sy,  0.0 ni, 47.7 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu2  : 89.1 us,  0.7 sy,  0.0 ni, 10.2 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu3  : 73.8 us,  1.1 sy,  0.0 ni, 25.1 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu4  : 16.3 us,  3.6 sy,  0.0 ni, 80.1 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu5  : 11.2 us,  2.6 sy,  0.0 ni, 86.1 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu6  : 79.7 us,  1.4 sy,  0.0 ni, 18.9 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu7  : 63.2 us,  1.0 sy,  0.0 ni, 35.7 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu8  :  7.7 us,  5.6 sy,  0.0 ni, 86.7 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu9  :  6.7 us,  3.9 sy,  0.0 ni, 89.4 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu10 :  6.4 us,  3.6 sy,  0.0 ni, 90.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu11 :  6.0 us,  4.9 sy,  0.0 ni, 89.1 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu12 :  5.7 us,  5.0 sy,  0.0 ni, 89.4 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu13 :  8.0 us,  4.8 sy,  0.0 ni, 87.2 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu14 : 11.8 us,  4.2 sy,  0.0 ni, 84.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu15 : 11.5 us,  4.2 sy,  0.0 ni, 84.4 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem:  13190558+total, 52510896 used, 79394688 free,   968680 buffers
KiB Swap: 13408256+total,        0 used, 13408256+free. 28238132 cached Mem

  PID USER      PR  NI    VIRT    RES    SHR S %CPU %MEM     TIME+  P COMMAND                                                                                                                                                 
17431 user     20   0 12.312g 9.604g 332848 R  0.0  7.6   1011:50  7 worker_7                                                                                                                                                
17430 user     20   0 12.312g 9.604g 332848 R  0.0  7.6 493:55.94  6 worker_6                                                                                                                                                
17429 user     20   0 12.312g 9.604g 332848 S 20.0  7.6 433:32.44  5 worker_5                                                                                                                                                
17428 user     20   0 12.312g 9.604g 332848 S 23.3  7.6 314:37.58  4 worker_4                                                                                                                                                
17427 user     20   0 12.312g 9.604g 332848 R  0.0  7.6 457:52.54  3 worker_3                                                                                                                                                
17426 user     20   0 12.312g 9.604g 332848 R 88.8  7.6   1822:39  2 worker_2                                                                                                                                                
17425 user     20   0 12.312g 9.604g 332848 R  0.0  7.6 549:01.50  1 worker_1                                                                                                                                                
17424 user     20   0 12.312g 9.604g 332848 R  0.0  7.6 381:33.97  0 worker_0        
  • 1
    Could you edit your question and clarify what the problem is? I must be missing something, but I can't understand what you are asking. – terdon Mar 12 at 18:09
  • Please edit your question and add this. Tell us how you know the process is running and how you know it's currently using more than 0% CPU. How do you know it isn't waiting for input, for example, or just not running? – terdon Mar 12 at 20:22
  • @terdon, the problem is there is a process that is definitely using cpu, but it shows 0% in top's output. For example cpu 7 is clearly doing work from the top part of top's output and the ONLY process running on cpu 7 is worker_7 and yet it shows 0.0% cpu usage. Does that clear this up or should I still edit the question? – Vadimski Mar 12 at 20:23
  • You should always edit your question to add more details. Comments are hard to read, easy to miss and can be deleted without warnings, so anything relevant should be added to the question where the next person can easily see it. Thanks! – terdon Mar 12 at 20:24

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.