Decision Optimization

Decision Optimization

Delivers prescriptive analytics capabilities and decision intelligence to improve decision-making.

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  • 1.  CPU time > wall clock time

    Posted Wed January 17, 2018 01:11 PM

    Originally posted by: usertim


    Hi, Im  solving  a MIP using Benders decomposition, using parameter 3 in python (cplex make the master and subproblems). Just for comparing, i used both CPU time and wall clock time (c.parameters.clocktype.set( 1 or 2)), I ended up seeing that CPU time was bigger than wall clock time (Eg. 37s  vs 23s). I used up to 8 cores (c.parameters.threads.set(8)) . Is it normal  that CPU time > wall clock time ?

     

    Thanks.

    Regards


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    #DecisionOptimization


  • 2.  Re: CPU time > wall clock time

    Posted Wed January 17, 2018 03:37 PM

    If you use more than one thread then it can easily happen that the CPU time exceeds the wallclock time. The CPU time is the total time the application spent on the CPUs. If the application runs on two CPUs at the same time then the times spent on the two CPUs are added.

    The wallclock time instead is just the elapsed real time in seconds.

    See also https://en.wikipedia.org/wiki/CPU_time


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    #DecisionOptimization