Don't take HPC-oriented performance timings with "time ./program", as that
measures all sorts of things that have nothing to do with application
performance. You should time the "while t < Tf" loops in both cases.
Jeff
On Mon, Oct 10, 2016 at 6:30 AM, Praveen C <[email protected]> wrote:
>
> Dear all
>
> I am trying out Chapel with some simple example to see how it fares with
MPI.
>
> I solve a linear advection equation in 2-d using Chapel and Petsc with a
finite volume method. The Petsc code makes use of Petsc vectors to handle
the MPI communication. I dont really solve any matrix problem.
>
> I have these two codes here
>
> https://github.com/cpraveen/cfdlab/tree/master/chapel/convect2d
> https://github.com/cpraveen/cfdlab/tree/master/petsc/convect2d
>
> Both codes are solving the same problem with same algorithm. I run these
codes on my 4-core macbook pro laptop as follows.
>
> Chapel 1.4
>
> time ./convect2d --n=100 --Tf=10.0 --cfl=0.4 --si=100000
>
>
> 3532 9.99
>
> 3533 9.99283
>
> 3534 9.99566
>
> 3535 9.99849
>
> 3536 10.0
>
>
> real 0m4.451s
>
> user 0m15.767s
>
> sys 0m0.599s
>
>
> Petsc 2.7.3 (MPI)
>
> time mpirun -np 4 ./convect -Tf 10.0 -da_grid_x 100 -da_grid_y 100 -cfl
0.4 -si 100000
>
>
> it, t = 3532, 9.990005
>
> it, t = 3533, 9.992833
>
> it, t = 3534, 9.995661
>
> it, t = 3535, 9.998490
>
> it, t = 3536, 10.000000
>
>
> real 0m1.677s
>
> user 0m6.370s
>
> sys 0m0.242s
>
>
> The Petsc (MPI) code is about 2.5 times faster than Chapel.
>
> I would like to know if I am making comparison in a fair manner ? Am I
using the best optimization flags ? These are present in the makefiles.
>
> With MPI, I used 4 processors but I did not specify anything with Chapel.
Is this a fair way to compare them ? If not what should be done ?
>
> Thanks
> praveen
>
>
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--
Jeff Hammond
[email protected]
http://jeffhammond.github.io/
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