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How to know the CPU and Memory usage (in terms of %) of a Process in Linux?

+5 votes
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How to know the CPU and Memory usage (in terms of %) of a Process in Linux?
posted Jan 8, 2014 by Salil Agrawal

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3 Answers

+2 votes

We can get the %CPU and %MEM usage of particular process using ps command.
Give the proper process id for that particular process.

Below is the sample output.

# ps -p 4599,1 --sort -rss -o comm,pmem,pcpu
COMMAND         %MEM       %CPU
dre_app          0.2       0.4
init             0.0       0.0

Other commands also available which gives the cpu, memory details which are top, mpstat (for cpu), pmap (for mem)

answer Feb 6, 2014 by Gurpreet Singh Matharoo
+1 vote

You need to parse out the data from /proc//stat. These are the first few fields (from Documentation/filesystems/proc.txt in your kernel source):

Contents of the stat files.

Field : Content

pid: process id
tcomm: filename of the executable
state : state (R is running, S is sleeping, D is sleeping in an
uninterruptible wait, Z is zombie, T is traced or stopped)
ppid: process id of the parent process
pgrp : pgrp of the process
sid : session id
tty_nr : tty the process uses
tty_pgrp: pgrp of the tty
flags : task flags
min_flt : number of minor faults
cmin_flt : number of minor faults with child's
maj_flt : number of major faults
cmaj_flt : number of major faults with child's
utime : user mode jiffies
stime : kernel mode jiffies
cutime : user mode jiffies with child's
cstime kernel mode jiffies with child's

You're probably after utime and/or stime. You'll also need to read the cpu line from /proc/stat, which looks like:

'cpu 192369 7119 480152 122044337 14142 9937 26747 0 0'

This tells you the cumulative CPU time that's been used in various categories, in units of jiffies. You need to take the sum of the values on this line to get a time_total measure.

Read both utime and stime for the process you're interested in, and read time_total from /proc/stat. Then sleep for a second or so, and read them all again. You can now calculate the CPU usage of the process over the sampling time, with:

user_util = 100 * (utime_after - utime_before) / (time_total_after - time_total_before);
sys_util = 100 * (stime_after - stime_before) / (time_total_after - time_total_before);

answer Jan 8, 2014 by Sandeep
+1 vote

Please use top command to get all details of CPU and memory usages like below column:

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND

answer Jan 14, 2014 by Amit Kumar Pandey
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