实时实时平均总CPU负载命令

Question

In my java program, I have connected to a remote server using Jsch, and now I need to get the Cpu utilization of that server. I have used iostat -c command to get the CPU details...;the details I got is as follows:

Linux 3.1.0-1.2-desktop (ccitsuse06)    10/05/2015      _i686_  (4 CPU)
avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0.06    0.00    0.03    0.00    0.00   99.91

I actually need the total average CPU load ; How can I get the same using commands? Is there any simple single command that gives me total average Cpu at real time... or do I need to parse results from these data? Again; what factors contribute to the total average cpu so that i can calculate. I have read previous similar questions but none of them cleared my doubts.

*Please note that It is the current/real time average CPU load that I require for my program and I want the command to be executed as accurately and as fast as possible..

I have been reading usage of awk, egrep, etc but still I'm clue less as to how to use this in command to achieve my desired result!

Answer 1

Try

mpstat -u | grep -A 1 '%idle' | tail -1 | sed -r 's/ +/ /g' | cut -d' ' -f12

If you want to understand what it's doing, you should try executing it bit by bit (start with just the first part, then add on the grep part, etc.).

This grabs all the stats using mpstat ; then takes just the relevant lines using grep ; gets rid of the header row using tail ; compresses extra spaces using sed ; then takes the 12th column using cut .

This will give you the idle reading, as a value out of 100. To turn this into a percentage figure for CPU usage, you'll need to subtract this value from 100.

Answer 2

To get an average CPU load over a period of time you need to look at the CPU used at the start and end of that period. You can sample the /proc/stat which has the amount of time each logical CPU has used, or you need to run a utility for the amount of time you want to sample.

eg

head -1 /proc/stat

prints

cpu  170661 1384 22478 7836920 3244 0 2645 0 0 0

From the docs, this is

cpu  3357 0 4313 1362393
     The amount of time, measured in units of USER_HZ
     (1/100ths of a second on most architectures, use
     sysconf(_SC_CLK_TCK) to obtain the right value), that
     the system spent in various states:

     user   (1) Time spent in user mode.

     nice   (2) Time spent in user mode with low priority
            (nice).

     system (3) Time spent in system mode.

     idle   (4) Time spent in the idle task.  This value
            should be USER_HZ times the second entry in the
            /proc/uptime pseudo-file.

     iowait (since Linux 2.5.41)
            (5) Time waiting for I/O to complete.

     irq (since Linux 2.6.0-test4)
            (6) Time servicing interrupts.

     softirq (since Linux 2.6.0-test4)
            (7) Time servicing softirqs.

     steal (since Linux 2.6.11)
            (8) Stolen time, which is the time spent in
            other operating systems when running in a
            virtualized environment

     guest (since Linux 2.6.24)
            (9) Time spent running a virtual CPU for guest
            operating systems under the control of the Linux
            kernel.

     guest_nice (since Linux 2.6.33)
            (10) Time spent running a niced guest (virtual
            CPU for guest operating systems under the
            control of the Linux kernel).

If you take the difference of these values between any two samples, you can the percentage of time busy.