Viewing CPU load in Linux environment

In Linux, CPU consumption, sorted by the greatest load, can be viewed using two commands: ps and top.

Important tip: The value in the "CPU" column in both commands is counted based on the load of one processor core. Thus, the sum of percentages on multi-core machines will be more than 100%. E.g. for a quad-core processor, the total percentage of consumption for all processes may not exceed 400%.

Let's consider each of the commands in more detail.

'ps' command

To start it, enter the following command into the OS console:

ps -aux --sort -pcpu

Example command output:

$ ps -aux --sort -rss
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
user      30799 51.2  8.1 2733764 285136 ?      Rl   09:25   5:30 /usr/lib/chromium-browser/chromium-browser --ppapi-flash-path=/usr/lib/pepperflashplugin-nonfree/libpepflashplayer.so --ppap
user       2800  0.1  6.6 9972812 234184 ?      Sl   oct31   1:26 /usr/bin/plasmashell --shut-up
user      31308  2.4  5.3 1767496 188672 ?      Sl   09:26   0:13 /usr/lib/chromium-browser/chromium-browser --type=renderer --enable-pinch --field-trial-handle=7228759356551874141,180166971
user      31011  3.9  5.3 1793296 186812 ?      Sl   09:25   0:25 /usr/lib/chromium-browser/chromium-browser --type=renderer --enable-pinch --field-trial-handle=7228759356551874141,180166971
user      31369  5.5  4.8 1378568 171328 ?      Sl   09:28   0:23 /usr/lib/libreoffice/program/soffice.bin --writer --splash-pipe=5
user      14442 12.1  4.2 1050808 150148 ?      Sl   01:19  60:04 /usr/lib/x86_64-linux-gnu/libexec/kscreenlocker_greet --graceTime 5000 --ksldfd 26
user      31111  0.9  3.8 1708496 134564 ?      Sl   09:25   0:06 /usr/lib/chromium-browser/chromium-browser --type=renderer --enable-pinch --field-trial-handle=7228759356551874141,180166971
user       1225  0.0  3.7 3639148 132092 ?      Sl   oct31   1:00 /usr/bin/plasmashell --shut-up
user      31078  0.6  3.7 1724480 130724 ?      Sl   09:25   0:03 /usr/lib/chromium-browser/chromium-browser --type=renderer --enable-pinch --field-trial-handle=7228759356551874141,180166971
user      30986  0.7  3.3 1717860 117660 ?      Sl   09:25   0:04 /usr/lib/chromium-browser/chromium-browser --type=renderer --enable-pinch --field-trial-handle=7228759356551874141,180166971
user       1216  1.7  3.2 3271220 113736 ?      Sl   oct31  20:36 kwin_x11

Important columns are:

  • USER     The user on whose behalf the process is running
  • PID         Process ID
  • %CPU    CPU load percentage

This output makes it clear that an instance of the dd program with PID = 31712 almost completely utilizes one core of the processor.

'top' command

Also, the CPU load can be viewed interactively using the top command. To start it, enter the following command into the OS console:

top

Example command output:

top - 15:13:56 up 8 days,  5:18,  4 users,  load average: 0,01, 0,04, 0,05
Tasks: 124 total,   1 running, 123 sleeping,   0 stopped,   0 zombie
%Cpu(s):  0,0 us,  0,0 sy,  0,0 ni, 99,9 id,  0,1 wa,  0,0 hi,  0,0 si,  0,0 st
KiB Mem:   2060916 total,  1714780 used,   346136 free,   184580 buffers
KiB Swap:   901116 total,        0 used,   901116 free,   999472 cached

  PID USER      PR  NI  VIRT  RES  SHR S  %CPU %MEM    TIME+  COMMAND
22684 root      20   0 24768 1476 1016 R   0,3  0,1   0:00.01 top
    1 root      20   0 15444  756  612 S   0,0  0,0   0:08.79 init
    2 root      20   0     0    0    0 S   0,0  0,0   0:00.00 kthreadd
    3 root      20   0     0    0    0 S   0,0  0,0   1:08.03 ksoftirqd/0
    5 root      20   0     0    0    0 S   0,0  0,0   0:00.00 kworker/u:0
    6 root      rt   0     0    0    0 S   0,0  0,0   0:00.77 migration/0
    7 root      rt   0     0    0    0 S   0,0  0,0   0:02.81 watchdog/0
    8 root      rt   0     0    0    0 S   0,0  0,0   0:00.77 migration/1
   10 root      20   0     0    0    0 S   0,0  0,0   0:04.40 ksoftirqd/1
   12 root      rt   0     0    0    0 S   0,0  0,0   0:02.40 watchdog/1
   13 root      rt   0     0    0    0 S   0,0  0,0   0:01.50 migration/2
   15 root      20   0     0    0    0 S   0,0  0,0   0:04.33 ksoftirqd/2
   16 root      rt   0     0    0    0 S   0,0  0,0   0:02.26 watchdog/2
   17 root      rt   0     0    0    0 S   0,0  0,0   0:00.49 migration/3
   19 root      20   0     0    0    0 S   0,0  0,0   0:03.73 ksoftirqd/3
   20 root      rt   0     0    0    0 S   0,0  0,0   0:02.21 watchdog/3
   21 root       0 -20     0    0    0 S   0,0  0,0   0:00.00 cpuset
   22 root       0 -20     0    0    0 S   0,0  0,0   0:00.00 khelper
   23 root      20   0     0    0    0 S   0,0  0,0   0:00.00 kdevtmpfs
   24 root       0 -20     0    0    0 S   0,0  0,0   0:00.00 netns
   25 root      20   0     0    0    0 S   0,0  0,0   0:01.84 sync_supers
   26 root      20   0     0    0    0 S   0,0  0,0   0:00.05 bdi-default
   27 root       0 -20     0    0    0 S   0,0  0,0   0:00.00 kintegrityd
   28 root       0 -20     0    0    0 S   0,0  0,0   0:00.00 kblockd
   30 root      20   0     0    0    0 S   0,0  0,0   0:08.20 kworker/2:1
   31 root      20   0     0    0    0 S   0,0  0,0   0:01.98 kworker/3:1
   32 root      20   0     0    0    0 S   0,0  0,0   0:00.32 khungtaskd
   33 root      20   0     0    0    0 S   0,0  0,0   0:00.00 kswapd0
   34 root      25   5     0    0    0 S   0,0  0,0   0:00.00 ksmd
   35 root      39  19     0    0    0 S   0,0  0,0   0:00.00 khugepaged
   36 root      20   0     0    0    0 S   0,0  0,0   0:00.00 fsnotify_mark
   37 root       0 -20     0    0    0 S   0,0  0,0   0:00.00 crypto
  103 root       0 -20     0    0    0 S   0,0  0,0   0:00.00 ata_sff
  111 root      20   0     0    0    0 S   0,0  0,0   0:00.00 scsi_eh_0
  114 root      20   0     0    0    0 S   0,0  0,0   0:00.01 scsi_eh_1
  115 root      20   0     0    0    0 S   0,0  0,0   0:15.02 kworker/u:1
  119 root       0 -20     0    0    0 S   0,0  0,0   0:00.00 mpt_poll_0
  137 root       0 -20     0    0    0 S   0,0  0,0   0:00.00 mpt/0
  165 root      20   0     0    0    0 S   0,0  0,0   0:00.00 scsi_eh_2
  169 root      20   0     0    0    0 S   0,0  0,0   0:11.68 kworker/3:2
  177 root      20   0     0    0    0 S   0,0  0,0   1:37.28 kworker/1:2
  207 root      20   0     0    0    0 S   0,0  0,0   0:07.77 flush-8:0
  213 root      20   0     0    0    0 S   0,0  0,0   0:21.32 jbd2/sda1-8
  214 root       0 -20     0    0    0 S   0,0  0,0   0:00.00 ext4-dio-unwrit
  355 root      20   0 24140 1468  816 S   0,0  0,1   0:00.06 udevd
  502 root      20   0 24100 1096  468 S   0,0  0,1   0:00.00 udevd
  503 root      20   0 24100 1028  408 S   0,0  0,0   0:00.00 udevd
  527 root       0 -20     0    0    0 S   0,0  0,0   0:00.00 kpsmoused
  528 root      20   0     0    0    0 S   0,0  0,0   0:04.36 kworker/2:2
  555 root       0 -20     0    0    0 S   0,0  0,0   0:00.00 ttm_swap
 1842 root      20   0  152m 8928 4548 S   0,0  0,4   8:15.13 vmtoolsd
 1885 root      20   0 60288 9396 6444 S   0,0  0,5   0:00.04 VGAuthService
 1979 root      20   0  199m 5016 4128 S   0,0  0,2   3:19.79 ManagementAgent

Important columns are:

  • USER     The user on whose behalf the process is running
  • PID         Process ID
  • %CPU    CPU load percentage

This output shows that two processes of Chromium browser use 40% of the capabilities of one of the CPU cores.