[OMPI users] question about run-time of a small program

[Gilles Gouaillardet]

Siegmar,


a noticeable difference is hello_1 does *not* sleep, whereas
hello_2_slave *does*

simply comment out the sleep(...) line, and performances will be identical


Cheers,

Gilles

Hi,
I have two versions of a small program. In the first one the process
with rank 0
calls the function "master()" and all other ranks call the function
"slave()" and in the second one I have two programs: one for the
master task and another
one for the slave task. The run-time for the second version is much
bigger than
the one for the first version. Any ideas why the version with two
separate
programs takes that long?
loki tmp 108 mpicc -o hello_1_mpi hello_1_mpi.c
loki tmp 109 mpicc -o hello_2_mpi hello_2_mpi.c
loki tmp 110 mpicc -o hello_2_slave_mpi hello_2_slave_mpi.c
loki tmp 111 /usr/bin/time -p mpiexec -np 3 hello_1_mpi
Process 0 of 3 running on loki
Process 1 of 3 running on loki
Process 2 of 3 running on loki
...
real 0.14
user 0.00
sys 0.00
loki tmp 112 /usr/bin/time -p mpiexec -np 1 hello_2_mpi : \
-np 2 hello_2_slave_mpi
Process 0 of 3 running on loki
Process 1 of 3 running on loki
Process 2 of 3 running on loki
...
real 23.15
user 0.00
sys 0.00
loki tmp 113 ompi_info | grep "Open MPI repo revision"
Open MPI repo revision: v3.0.0rc2
loki tmp 114
Thank you very much for any answer in advance.
Kind regards
Siegmar
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