System monitor app shows that ubuntu uses only one core 100% (constantly over 99%) and the other 7 are not used at all (0%) also -while one core being at 100%- checking on the processes tab (which I display all + dependencies) all the processes show 0% usage... so what is happening here? At first I thought there is some bug or incompatibility with the app..

but now after opening a few more firefox tabs or trying to do parallel stuff (like installing something while watching a video or what not) ubuntu windows freeze one at a time and unfreeze continue what they are doing including console...

So I guess System Monitor app is right and only 1 core of my cpu is used...

lscpu outputs

Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                8
On-line CPU(s) list:   0-7
Thread(s) per core:    2
Core(s) per socket:    4
Socket(s):             1
NUMA node(s):          1
Vendor ID:             AuthenticAMD
CPU family:            21
Model:                 2
Model name:            AMD FX(tm)-8320 Eight-Core Processor
Stepping:              0
CPU MHz:               1400.000
CPU max MHz:           3500,0000
CPU min MHz:           1400,0000
BogoMIPS:              6984.78
Virtualization:        AMD-V
L1d cache:             16K
L1i cache:             64K
L2 cache:              2048K
L3 cache:              8192K
NUMA node0 CPU(s):     0-7

lshw -class cpu outputs

   product: AMD FX(tm)-8320 Eight-Core Processor
   vendor: Advanced Micro Devices [AMD]
   physical id: 1
   bus info: cpu@0
   size: 3500MHz
   capacity: 3500MHz
   width: 64 bits
   capabilities: fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall  nx mmxext fxsr_opt pdpe1gb rdtscp x86-64 constant_tsc rep_good nopl nonstop_tsc extd_apicid aperfmperf pni pclmulqdq monitor ssse3 fma cx16 sse4_1 sse4_2 popcnt aes xsave avx f16c lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs xop skinit wdt lwp fma4 tce nodeid_msr tbm topoext perfctr_core perfctr_nb arat cpb hw_pstate npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold vmmcall bmi1 cpufreq

I have also a Nvidia GTX 650 Ti as a GPU

I have installed both AMD microcode driver for the CPU and the Nvidia driver.


This issue may be caused because of some application You are running might be a monothread applications, therefore they will use and max out only single core of Your CPU.

Could You post TOP result?

You can always reassign process to the other cpu core using

taskset -c 0 application

It can help to check if You can use other cpu cores with other applications.

To get more accurate real-time info on whats going on You can download htop package

sudo apt-get install htop
| improve this answer | |
  • Yea but shouldnt other applications choose an other core if one is like over 99%? I tell you all the time core 1,2,3,4,5,6,7 are on 0% usage according to System monitor and only core0 is 100%... this happens if I use only one app no apps or multiple apps Anyway I downloaded htop it shows on the process tab that 70%-80% of my cpu (although at the top is shows only one green core at 100%and the rest using gray color at 0% ) is used by root under command /usr/bin/pyton /usr/share/system-config-lvm/system-config-lvm.py – papajo Apr 2 '16 at 12:37
  • and ~20% is used by firefos under my username. on the top right corner it sais tasks 136,396 thr 3 running load average 1.6 2.02 2.08 – papajo Apr 2 '16 at 12:40
  • You should have Your cores listed on the top left corner as 1, 2, 3, 4, 5, 6, 7, 8 (assuming 1=0, 2=1) – Eska Apr 2 '16 at 12:41
  • yea and as I mentioned in the parethesis of my comment above) only core 1 is colored green and runs at 100% the other cores from 2 to 8 are colored gray and are at 0% – papajo Apr 2 '16 at 12:48
  • and on the tabs under the top the process that uses 80% cpu (I dont understand how it derives the "80%" result since only one core is used to 100% according to the same prog) is a process with PID 3758 made by user root and commad is: /usr/bin/pyton /usr/share/system-config-lvm/system-config-lvm.py – papajo Apr 2 '16 at 12:50

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