How to determine CPU time required by processes

[colinragoo]

Hi All,
I am working on an optimization algorithm for processing parallel jobs for a school project and am wondering if its possible to get the total time required by each process in the scheduling cycle so that I can adjust the time quantum (reduce interactive processes time quantum) to speedup the parallel processes.

Thanks

[Rubberman]

You can use the time command to start a process, which when the process finishes will output the amount of system, user, and elapsed time used by the process. Usually there is a built-in shell time command, but there is also an executable version with some more features, /usr/bin/time.

[colinragoo]

The time command gives the time output after the process has executed, is there a way to get the amount of time the process needs to execute before the process is actually executed? Are processes aware of their time quantum needs? The algorithm needs to know the time requirements of the process so that it can optimize the scheduling based on this information. See my original post.

Thanks

[Rubberman]

The time command gives the time output after the process has executed, is there a way to get the amount of time the process needs to execute before the process is actually executed? Are processes aware of their time quantum needs? The algorithm needs to know the time requirements of the process so that it can optimize the scheduling based on this information. See my original post.

Thanks

The time command(s) won't analyze a program to determine how much time is required to run its various functions. After all, determining all the possible execution paths through a non-trivial program, especially a server-type program, may be an np-hard type of problem in that the number of possible execution paths can be indeterminate.

That said, there are profiling tools available that can look at executing processes and help determine time requirements as the process runs. Some are open-source (the gnu profiler that comes with the gcc compiler suite, for example) and others are commercial (such as Quantify from IBM-Rational Software). When I need to do real performance analysis for complex system software, I prefer tools such as Quantify that utilize object-code insertion techniques to get absolute performance metrics for analysis, vs. compiled-in time-slice techniques used by most open-source tools and traditional profilers.