Skip to content

Instantly share code, notes, and snippets.

What would you like to do?
How much work the poor CPU needs to do when we echo 4-characters string in the Linux console?

And the answer is:

688471 instructions

--@--:~$ uname -a
Linux 3.13.0-101-generic #148-Ubuntu SMP Thu Oct 20 22:09:17 UTC 2016 i686 i686 i686 GNU/Linux
--@--:~$ sudo perf stat echo test

 Performance counter stats for 'echo test':

          0,898550 task-clock (msec)         #    0,633 CPUs utilized          
                 2 context-switches          #    0,002 M/sec                  
                 1 cpu-migrations            #    0,001 M/sec                  
               151 page-faults               #    0,168 M/sec                  
           1848617 cycles                    #    2,057 GHz                    
   <not supported> stalled-cycles-frontend 
   <not supported> stalled-cycles-backend  
            688471 instructions              #    0,37  insns per cycle        
            126235 branches                  #  140,487 M/sec                  
     <not counted> branch-misses           

       0,001418434 seconds time elapsed
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.