If you are interested in finding out which process is consuming most of your system resources i.e. CPU cycles or memory, then read on.

In Linux you can view the top 10 memory consuming processes by using certain ps command options. Let’s see how.

For those who are too eager, here are the quick and readymade commands:

Top 10 memory consuming processes

ps axo %mem,comm,pid,euser | sort -nr | head -n 10

Top 10 process according to CPU load

ps axo pcpu,comm,pid,euser | sort -nr | head -n 10

How it Works

It is very interesting to know how these commands actually work. Let’s see it here.

To see every process in your system you can use the command

ps ax

To see every process with a user-defined format:

ps axo stat,euser,ruser,pmem,ppid,pid,pcpu,comm

The output will look like

STAT EUSER RUSER %MEM PPID PID %CPU COMMAND
Ss root root 0.0 0 1 0.0 init
S< root root 0.0 1 2 0.0 migration/0
SN root root 0.0 1 3 0.0 ksoftirqd/0
S< root root 0.0 1 4 0.0 watchdog/0
S< root root 0.0 1 5 0.0 migration/1
SN root root 0.0 1 6 0.0 ksoftirqd/1
S< root root 0.0 1 7 0.0 watchdog/1
S< root root 0.0 1 8 0.0 migration/2
SN root root 0.0 1 9 0.0 ksoftirqd/2
…

The option ax causes to list all the process while the o option requires a user defined format to display in the output of the command

It accepts certain keywords as STANDARD FORMAT SPECIFIERS. Some of the useful formats are

euser – > Effective User ID.
stat – > Process State Descriptor
ruser – > Real User ID.
pmem – > percentage of Memory consumed
ppid – > Parent Process ID
pid – > Process ID
pcpu – > Percentage of CPU
comm – > command or the process name.

For an extended list of Format Specifiers, you can refer to the manual of ps command

man ps

The format descriptors pcpu and pmem are useful to us.

ps axo pcpu,pmem,comm | head
%CPU %MEM COMMAND
0.0 0.0 init
0.0 0.0 migration/0
0.0 0.0 ksoftirqd/0
0.0 0.0 watchdog/0
0.0 0.0 migration/1
0.0 0.0 ksoftirqd/1
0.0 0.0 watchdog/1
0.0 0.0 migration/2
0.0 0.0 ksoftirqd/2

Top 10 Memory consuming process

The command is

ps axo %mem,comm,pid,euser | sort -nr | head -n 10

1.8 mysqld 12406 mysql
1.7 java 21933 acladmin
0.2 puplet 21489 root
0.1 yum-updatesd 11599 root
0.1 nautilus 21462 root
…

We displayed the percentage of Memory consumption in the first field. That formed the input of the sort command which sorted the first columns according to number and then we displayed only the 5 process from the top using head.

Top 10 CPU consuming process

The command is

ps axo pcpu,comm,pid,euser | sort -nr | head -n 10

4.3 cmanicd 8491 root
2.2 java 21933 acladmin
0.6 unicelpush1sc 14236 acladmin
0.4 unicelpush1ss 14527 acladmin
0.3 snmpd 7036 root
…

We used the same trick here but the pcpu specifier is used instead of the pmem which displays the percentage CPU utilization.

After knowing the culprit process you might want to kill the process by sending signals. Check out how to send signals to process using kill command.

Find Out Top 10 CPU / Memory consuming processes