perf: comparing "CPU performance / CPU impact" of two binaries?

perf: comparing "CPU performance / CPU impact" of two binaries?

[Tomasz Chmielewski]

Let's say I have two binaries which convert complex data from one format 
to another.

I will run them on a busy server at low priority and I don't really care 
if one is faster than the other - I want to know which of them will have 
lower "CPU impact" to perform the same task.


binary_1:

    26879408.172126      task-clock:u (msec)       #    0.709 CPUs 
utilized
                  0      context-switches:u        #    0.000 K/sec
                  0      cpu-migrations:u          #    0.000 K/sec
         1142192473      page-faults:u             #    0.042 M/sec
     81241884199345      cycles:u                  #    3.022 GHz         
              (83.59%)
     65593453047217      stalled-cycles-frontend:u #   80.74% frontend 
cycles idle     (83.59%)
     34800591044061      stalled-cycles-backend:u  #   42.84% backend 
cycles idle      (67.09%)
     98783244945290      instructions:u            #    1.22  insn per 
cycle
                                                   #    0.66  stalled 
cycles per insn  (83.64%)
     18250463170335      branches:u                #  678.976 M/sec       
              (83.60%)
       169450790563      branch-misses:u           #    0.93% of all 
branches          (83.59%)

    37911.679793230 seconds time elapsed


binary_2:

    33134123.016486      task-clock:u (msec)       #    1.071 CPUs 
utilized
                  0      context-switches:u        #    0.000 K/sec
                  0      cpu-migrations:u          #    0.000 K/sec
         1947142971      page-faults:u             #    0.059 M/sec
    105227191042973      cycles:u                  #    3.176 GHz         
              (83.69%)
     80721331715962      stalled-cycles-frontend:u #   76.71% frontend 
cycles idle     (83.69%)
     46245245856602      stalled-cycles-backend:u  #   43.95% backend 
cycles idle      (67.25%)
    140459525725760      instructions:u            #    1.33  insn per 
cycle
                                                   #    0.57  stalled 
cycles per insn  (83.93%)
      9187630340020      branches:u                #  277.286 M/sec       
              (83.70%)
       112107883833      branch-misses:u           #    1.22% of all 
branches          (83.69%)

    30949.033426941 seconds time elapsed


As you can see, binary_1 was executing for 37911 seconds, and binary_2 
for 30949 seconds.

On the other hand, binary_2 used more cycles and instructions.


Because I will be running it on a busy server, I think that binary_1 
will have lower impact on the CPU (and, other tasks). Is my reasoning 
correct?


Tomasz Chmielewski
https://lxadm.com