When I execute following command to get cpu usage , I get nice + user cpu usage.
top -b -n1 | grep "Cpu(s)" | awk '{print $2 + $4}'
Output:
14.5
Here I am getting problem is that the output depends on top command thus it doesn't change instantly as top command. So I am not getting correct cpu instantly. It gives same output and not changing.
I want to get real-time cpu usage in output. Please help me to improve my command.
If you can afford a delay of one second, this will print CPU usage as a simple percentage:
echo $[100-$(vmstat 1 2|tail -1|awk '{print $15}')]
(Without the one-second delay, vmstat can only print average values since boot.)
vmstat 1 2 like this: echo $[100-$(vmstat 1 2|tail -1|awk '{print $15}')] Otherwise your vmstat is going to give values since boot which is likely not what you're after.
– Joe
Dec 05 '15 at 23:21
This is a known issue with top. As explained here, the 1st iteration of top -b returns the percentages since boot, we therefore need at least two iterations (-n 2) to get the current percentage. To speed things up, you can set the delay between iterations to 0.01. top splits CPU usage between user, system processes and nice processes, we want the sum of the three. Finally, you grep the line containing the CPU percentages and then use gawk to sum user, system and nice processes:
top -bn 2 -d 0.01 | grep '^%Cpu' | tail -n 1 | gawk '{print $2+$4+$6}'
----- ------ ----------- --------- ----------------------
| | | | |------> add the values
| | | |--> keep only the 2nd iteration
| | |----------------> keep only the CPU use lines
| |----------------------------> set the delay between runs
|-----------------------------------> run twice in batch mode
top will report the % usage as a percentage of a single CPU. This means you will often get much higher percentages. See point 9 here.
– terdon
Jul 19 '14 at 13:08
top in interactive mode (just run top) and, once there, hit I (shift + i) to see a breakdown by cores.
– terdon
Jul 19 '14 at 13:19
grep -c processor /proc/cpuinfo return? If that's 1 you have a buggy top but that's very unlikely.
– terdon
Jul 19 '14 at 13:24
top itself can actually cause a spike in CPU usage.
– terdon
Jul 19 '14 at 13:41
I have tried several ways, but this seems to me the most accurate:
cat <(grep 'cpu ' /proc/stat) <(sleep 1 && grep 'cpu ' /proc/stat) | awk -v RS="" '{print ($13-$2+$15-$4)*100/($13-$2+$15-$4+$16-$5)}'
Got it from here
%.1f, which in my opinion is more human readable and useful if you use that output in other scripts.
– lepe
Dec 04 '19 at 09:04
watch to be able to get overall cpu usage updated every couple seconds?
– Naveen Reddy Marthala
Dec 25 '21 at 17:43
watch, but I guess its possible.
– lepe
Dec 27 '21 at 05:47
I needed CPU usage per core and used mpstat from the sysstat package.
sudo apt install sysstat
CPU0 Utilization in %:
echo 100 - $(mpstat -P 0 | tail -1 | awk '{print $13}') | bc
CPU1 Utilization in %:
echo 100 - $(mpstat -P 1 | tail -1 | awk '{print $13}') | bc
Change the -P X if you have more than 2 cores.
With a very small delay (500 ms approx), the current CPU usage in % can be found out using the following command
awk '{u=$2+$4; t=$2+$4+$5; if (NR==1){u1=u; t1=t;} else print ($2+$4-u1) * 100 / (t-t1) "%"; }' <(grep 'cpu ' /proc/stat) <(sleep 0.5;grep 'cpu ' /proc/stat)
