top command

By default top command displays the processes in the order of CPU usage.
[root@boost ~]# top
top - 11:37:23 up  2:08,  3 users,  load average: 0.01, 0.00, 0.00
Tasks: 330 total,   1 running, 329 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.1%us,  0.1%sy,  0.0%ni, 99.5%id,  0.3%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:   7893520k total,  3663532k used,  4229988k free,   139728k buffers
Swap: 18431992k total,        0k used, 18431992k free,  2917144k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
    1 root      20   0 19248 1428 1156 S  0.0  0.0   0:01.58 init
    2 root      20   0     0    0    0 S  0.0  0.0   0:00.00 kthreadd
    3 root      RT   0     0    0    0 S  0.0  0.0   0:00.00 migration/0
    4 root      20   0     0    0    0 S  0.0  0.0   0:00.03 ksoftirqd/0
    5 root      RT   0     0    0    0 S  0.0  0.0   0:00.00 watchdog/0
    6 root      RT   0     0    0    0 S  0.0  0.0   0:00.00 migration/1
    7 root      20   0     0    0    0 S  0.0  0.0   0:00.00 ksoftirqd/1
    8 root      RT   0     0    0    0 S  0.0  0.0   0:00.00 watchdog/1