In Linux, the command top will show you an aggregation of the CPU usage by default. If your processor is multicore and you want to see the statistics on each core of that multi-core processor then you can do this within the top.
Normal top command output:
top - 12:54:17 up 90 days, 18:40, 2 users, load average: 0.24, 0.33, 0.41 Tasks: 737 total, 1 running, 736 sleeping, 0 stopped, 0 zombie Cpu(s): 0.6%us, 0.2%sy, 0.0%ni, 99.2%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 98956160k total, 95395364k used, 3560796k free, 25053208k buffers Swap: 100663292k total, 152048k used, 100511244k free, 32792224k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 64805 webfrm 20 0 364m 19m 9908 S 10.0 0.0 0:03.08 phpfcgi 5315 root 0 -20 52176 16m 1488 S 1.0 0.0 1342:57 scopeux 64775 postgres 20 0 308m 45m 40m S 0.7 0.0 0:28.46 postgres 64736 postgres 20 0 308m 45m 39m S 0.3 0.0 0:28.49 postgres 64738 webfrm 20 0 877m 42m 11m S 0.3 0.0 0:18.39 frm.fcgi 64739 webfrm 20 0 877m 42m 11m S 0.3 0.0 0:17.74 frm.fcgi 64745 webfrm 20 0 877m 28m 11m S 0.3 0.0 0:18.51 frm.fcgi 64747 webfrm 20 0 877m 42m 11m S 0.3 0.0 0:17.86 frm.fcgi 64748 webfrm 20 0 877m 42m 11m S 0.3 0.0 0:16.71 frm.fcgi 64754 webfrm 20 0 877m 42m 11m S 0.3 0.0 0:21.09 frm.fcgi 64759 postgres 20 0 309m 45m 39m S 0.3 0.0 0:28.11 postgres 64761 postgres 20 0 309m 46m 40m S 0.3 0.0 0:28.90 postgres 64762 postgres 20 0 308m 46m 40m S 0.3 0.0 0:30.01 postgres
After running the top command hit the 1 (numeric 1) and you will be able to see the usage of all the CPUs individually. In this case, my server has 24 CPUs which are being shown after hitting the key 1.
top - 12:55:06 up 90 days, 18:41, 2 users, load average: 0.35, 0.34, 0.41
Tasks: 737 total, 1 running, 736 sleeping, 0 stopped, 0 zombie
Cpu0 : 3.7%us, 1.1%sy, 0.0%ni, 95.2%id, 0.0%wa, 0.0%hi, 0.1%si, 0.0%st
Cpu1 : 0.2%us, 0.8%sy, 0.0%ni, 99.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu2 : 1.1%us, 0.2%sy, 0.0%ni, 98.6%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu3 : 0.1%us, 0.2%sy, 0.0%ni, 99.8%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu4 : 0.1%us, 0.3%sy, 0.0%ni, 99.4%id, 0.1%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu5 : 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu6 : 0.1%us, 0.1%sy, 0.0%ni, 99.6%id, 0.1%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu7 : 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu8 : 0.0%us, 0.0%sy, 0.0%ni, 99.8%id, 0.1%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu9 : 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu10 : 0.2%us, 0.1%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu11 : 0.0%us, 0.2%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu12 : 0.8%us, 1.0%sy, 0.0%ni, 98.2%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu13 : 0.1%us, 0.4%sy, 0.0%ni, 99.3%id, 0.1%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu14 : 1.2%us, 0.4%sy, 0.0%ni, 98.4%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu15 : 1.9%us, 0.3%sy, 0.0%ni, 97.8%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu16 : 0.1%us, 0.1%sy, 0.0%ni, 99.8%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu17 : 0.1%us, 0.1%sy, 0.0%ni, 99.8%id, 0.1%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu18 : 0.7%us, 0.6%sy, 0.0%ni, 98.5%id, 0.2%wa, 0.0%hi, 0.1%si, 0.0%st
Cpu19 : 0.4%us, 0.2%sy, 0.0%ni, 99.3%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu20 : 0.1%us, 0.0%sy, 0.0%ni, 99.9%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu21 : 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu22 : 0.4%us, 0.2%sy, 0.0%ni, 99.3%id, 0.0%wa, 0.0%hi, 0.1%si, 0.0%st
Cpu23 : 0.1%us, 0.3%sy, 0.0%ni, 99.6%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 98956160k total, 95411972k used, 3544188k free, 25053280k buffers
Swap: 100663292k total, 152048k used, 100511244k free, 32799164k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
7 root RT 0 0 0 0 S 21.9 0.0 1008:16 migration/1
5315 root 0 -20 52176 16m 1488 S 9.4 0.0 1342:59 scopeux
64760 postgres 20 0 309m 46m 40m S 1.0 0.0 0:28.07 postgres
64767 postgres 20 0 309m 45m 39m S 1.0 0.0 0:27.99 postgres
116953 root 20 0 308m 11m 9248 S 1.0 0.0 0:00.03 html2pdf
64745 webfrm 20 0 877m 28m 11m S 0.7 0.0 0:18.56 frm.fcgi
64749 webfrm 20 0 876m 24m 10m S 0.7 0.0 0:16.41 frm.fcgi
64756 webfrm 20 0 877m 41m 10m S 0.7 0.0 0:17.06 frm.fcgi