# iotop -h
  -h, --help            show this help message and exit
  -b, --batch           non-interactive mode
  -n NUM, --iter=NUM    number of iterations before ending [infinite]
  -d SEC, --delay=SEC   delay between iterations [1 second]
  -k, --kilobytes       use kilobytes instead of a human friendly unit
  -t, --time            add a timestamp on each line (implies --batch)
  -q, --quiet           suppress some lines of header (implies --batch)

# iotop
Total DISK READ :       0.00 B/s | Total DISK WRITE :       0.00 B/s
Actual DISK READ:       0.00 B/s | Actual DISK WRITE:       0.00 B/s
  TID  PRIO  USER     DISK READ  DISK WRITE  SWAPIN     IO>    COMMAND
    1 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % systemd --switched-root --system --deserialize 21
    2 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [kthreadd]
    3 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [ksoftirqd/0]
    5 be/0 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [kworker/0:0H]
    6 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [kworker/u2:0]
    7 rt/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [migration/0]
    8 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [rcu_bh]
    9 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [rcuob/0]
   10 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [rcu_sched]
   11 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [rcuos/0]
   12 rt/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [watchdog/0]
   13 be/0 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [khelper]
(abbr)

# iotop -t
23:27:42 Total DISK READ :       0.00 B/s | Total DISK WRITE :       0.00 B/s
23:27:42 Actual DISK READ:       0.00 B/s | Actual DISK WRITE:       0.00 B/s
    TIME  TID  PRIO  USER     DISK READ  DISK WRITE  SWAPIN      IO    COMMAND
23:27:42     1 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % systemd --switched-root --system --deserialize 21
23:27:42     2 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [kthreadd]
23:27:42     3 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [ksoftirqd/0]
23:27:42     5 be/0 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [kworker/0:0H]
23:27:42     6 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [kworker/u2:0]
23:27:42     7 rt/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [migration/0]
23:27:42     8 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [rcu_bh]
23:27:42     9 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [rcuob/0]
23:27:42    10 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [rcu_sched]
23:27:42    11 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [rcuos/0]
23:27:42    12 rt/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [watchdog/0]