Unix command to find CPU Utilization

Posted on in Categories , last updated January 13, 2007

Q. I am using Solaris UNIX. How do I find out CPU Utilization under Sun Solaris UNIX?

A. Under Sun Solaris UNIX (and other UNIX oses like HP-UX and *BSD oses) you can use following commands to gather CPU information:

=> sar : System activity reporter

=> mpstat : Report per-processor or per-processor-set statistics

=> ps / top commands

Note: Linux specific CPU utilization information is here. Following information applies to UNIX only.

UNIX sar command examples

General syntax is as follows:
sar t [n]
In the first instance, sar samples cumulative activity counters in the operating system at n intervals of t seconds, where t should be 5 or greater. If t is specified with more than one option, all headers are printed together and the output may be difficult to read.

Task: Display today’s CPU activity, use

# sar

Task:Watching system activity evolve i.e. reports CPU Utilization

# sar -u 12 5


  • -u 12 5: Comparison of CPU utilization; 12 seconds apart; 5 times.

Output includes:

  1. %usr: User time (% of CPU)
  2. %sys: System time (% of CPU)
  3. %wio: Percent of CPU running idle with a process waiting for block I/O
  4. %idle: Percent of CPU that is idle

Task: You can watch CPU activity evolve for 10 minutes and save data

# sar -o file-name 60 10

Task: You can just sar and logout and let the report store in files

# nohup sar -A -o output-file 60 10 1>/dev/null 2>&1 &
Note to display data stored in output-file pass -f option to sar command:
# sar -f output-file

UNIX mpstat example

Type the following command to display per-processor statistics; 12 seconds apart; 5 times
# mpstat 12 5

You can also use traditional ps and top command:
# top
# ps -e -o pcpu -o pid -o user -o args

Read man pages of ps, top, mpstat and sar for more information.

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on Twitter, Facebook, Google+.

14 comment

  1. I have Unix system with 32 CPU and 32 GB memory. My application is installed on Websphere. Looks like only 1 processor is allocated to my application out of 32 cpu. Is it possible to allocate multiple processors for my application. The system always shows 90% CPU idle time and more than 20 G free memory. How can I utilise this memory and cpu time to get better performance.

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