How to compute CPU time for a particular process?

[rakeshp]

Hello,

I have a fortran code, which I run on a multi-user Linux server. Since there are multiple users working on this server, I want to know, How much cpu time does my application takes to complete? Although I am able to calculate CPU clock time, I also need to know the total CPU time required for entire simulation to get completed. Is there any command or code, with help of which this can be achieved?

Thanks

Regards
Rakesh Patil

[zombykillah]

Hi rakeshp,

Don't know if it helps you.
When I wanna know the process time of a process I use the bash command "ps -ef" it will list all processes with their start time, used cpu time, PID, Parent PID and so on.

Don't know if there's a fortran code for it.

[drl]

Hi.

See man time. The time command runs commands for you and produces 3 times, like so (with bash):

time burn 10

producing:

real	0m10.727s
user	0m9.877s
sys	0m0.000s

The burn is a (local) example, you can use almost any command in its place. So if you compile your Fortran code and have the final executable on file a.out, then you would use:

time ./a.out

If you are using a csh family shell, the name, time, is the same , but output differs in format:

time burn 10
9.868u 0.004s 0:10.53 93.6%	0+0k 0+0io 0pf+0w

Best wishes ... cheers, drl

[drl]

Hi.

If you wanted to time sections of your code in modern Fortran, say Fortran-90, you could use some standard library routines, such as cpu_time on file one.f90:

     program main
       real :: my_sum, t1, t2, harvest(1000000)
       write(6,*) " Hello, world from fortran."
       call cpu_time(t1)
       call random_number(harvest)
       my_sum = sum ( harvest )
       call cpu_time(t2)
       call a( t2-t1 )
     end
     subroutine a ( t )
       real :: t
       write(6,*) " The time taken for code is ", t
       write(6,fmt="(a,f6.2)") "  The time taken for code is ", t
       return
     end

then using:

gfortran one.f90
./a.out

produces:

  Hello, world from fortran.
  The time taken for code is   3.60019989E-02
  The time taken for code is   0.04

This was done in the context:

OS, ker|rel, machine: Linux, 2.6.26-2-amd64, x86_64
Distribution        : Debian GNU/Linux 5.0.8 (lenny) 
gfortran GNU Fortran (Debian 4.3.2-1.1) 4.3.2

Example adapted from Modern Fortran Explained, Metcalf, et al, Oxford 2011, page 181.

Best wishes ... cheers, drl