0 Replies Latest reply on Sep 26, 2010 2:11 AM by emyict

    performance issue on Core 2 duo

    emyict

      Core 2 Duo  should have at least 2-3 integer funtion units , and it can fetch and decode at least 3-4 ops per cycle .  But I made some experiments on my laptop which is core 2 duo . I really can't understand the results. some one can give me help ?

       

      the main loop is as following

              addl $1,%eax                    # [0]
              cmpl %esi,%eax                  # [1]
              jl .Lt_11_4354                  # [77]      runtime 0.46s

      I add 1 to 7 "nop"  ops in it , the runtime will increase from 0.63s to 1.36s step by step .  This result shows that nop can't be handled more in parallel ?

       

      When I substitute nop with integer addl, the same thing happen .

       

      How to understand on Core 2 Duo . The results show a different core type which is difficult to understand ? Could  Some one please give me some suggestion?

       

      CPU: Intel(R) Core(TM)2 Duo CPU     T8100  @ 2.10GHz
      OS: federa ,Linux version 2.6.33.3-85.fc13.x86_64