Retrieve CPU usage and memory usage of a single process on Linux?
ps -p <pid> -o %cpu,%mem,cmd
(You can leave off "cmd" but that might be helpful in debugging).
Note that this gives average CPU usage of the process over the time it has been running.
How to calculate the CPU usage of a process by PID in Linux from C?
You need to parse out the data from /proc/<PID>/stat
. These are the first few fields (from Documentation/filesystems/proc.txt
in your kernel source):
Table 1-3: Contents of the stat files (as of 2.6.22-rc3)
..............................................................................
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);
Make sense?
Retrieve CPU usage and memory usage of a single process on Linux?
ps -p <pid> -o %cpu,%mem,cmd
(You can leave off "cmd" but that might be helpful in debugging).
Note that this gives average CPU usage of the process over the time it has been running.
overall CPU usage and Memory(RAM) usage in percentage in linux/ubuntu
You can use top
and/or vmstat
from the procps package.
Use vmstat -s
to get the amount of RAM on your machine (optional), and
then use the output of top
to calculate the memory usage percentages.
%Cpu(s): 3.8 us, 2.8 sy, 0.4 ni, 92.0 id, 1.0 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem : 24679620 total, 1705524 free, 7735748 used, 15238348 buff/cache
KiB Swap: 0 total, 0 free, 0 used. 16161296 avail Mem
You can also do this for relatively short output:
watch '/usr/bin/top -b | head -4 | tail -2'
A shell pipe that calculates the current RAM usage periodically is
watch -n 5 "/usr/bin/top -b | head -4 | tail -2 | perl -anlE 'say sprintf(\"used: %s total: %s => RAM Usage: %.1f%%\", \$F[7], \$F[3], 100*\$F[7]/\$F[3]) if /KiB Mem/'"
(CPU + Swap usages were filtered out here.)
This command prints every 5 seconds:
Every 5.0s: /usr/bin/top -b | head -4 | tail -2 | perl -anlE 'say sprintf("u... wb3: Wed Nov 21 13:51:49 2018
used: 8349560 total: 24667856 => RAM Usage: 33.8%
Related Topics
Difference Between Using 'Sh' and 'Source'
Find Multiple Files and Rename Them in Linux
Maximum Number of Processes in Linux
How to Configure Apache 2 to Run Perl Cgi Scripts
Setting Up Ftp on Amazon Cloud Server
How to Find the Last Field Using 'Cut'
Error When Using Git Credential Helper With Gnome-Keyring as Sudo
Automating Running Command on Linux from Windows Using Putty
Can Awk Patterns Match Multiple Lines
Why Is a Tilde in a Path Not Expanded in a Shell Script
Shell Command to Tar Directory Excluding Certain Files/Folders
How to Copy Commits from One Git Repo to Another
How to Change 'Rpath' in an Already Compiled Binary
Sort a List With Lowercase First
Awk or Sed to Remove All Text After X Occurence in Each Line of File