Starting MPD on a multicore processor machine

[Elbert]

Hi,
I'm using MPI for the first time. The sample program runs fine as a
single process. But when I run it as distributed on a quad-core linux
machine 'mpirun -np 4 pi' I get the following message:

mpiexec_xyz.edu: cannot connect to local mpd (/tmp/mpd2.console_abc);
possible causes:
1. no mpd is running on this host
2. an mpd is running but was started without a "console" (-n option)
In case 1, you can start an mpd on this host with:
mpd &
and you will be able to run jobs just on this host.
For more details on starting mpds on a set of hosts, see
the MPICH2 Installation Guide.

I created a .mpd.config file containing the var.
MPD_SECRETWORD=<secretword> and launched mpd in background. When I
run the mpirun command, it gives the error: "problem with execution of
pi: [Errno 2] No such file or directory"

Could you please point me to a solution. I guess on multicore
machines only one mpd daemon is started.
An early response would be appreciated.

Thanks much,
Elbert

[Michael Hofmann]

Post by Elbert
I created a .mpd.config file containing the var.
MPD_SECRETWORD=3D<secretword> and launched mpd in background. When I
run the mpirun command, it gives the error: "problem with execution of=
pi: [Errno 2] No such file or directory"

Try to use "./pi" instead of "pi" in your mpirun command.

If this fails too, try something like "mpirun -np 4 pwd" to find out wha=
t is the current working directory. Then you can specify the correct loc=
ation of your executable file.

Post by Elbert
I guess on multicore machines only one mpd daemon is started.

Yes.


Michael

[Elbert]

Post by Michael Hofmann

Post by Elbert
I created a .mpd.config file containing the var.
MPD_SECRETWORD=<secretword> and launched mpd in background. When I
run the mpirun command, it gives the error: "problem with execution of
pi: [Errno 2] No such file or directory"

Try to use "./pi" instead of "pi" in your mpirun command.
If this fails too, try something like "mpirun -np 4 pwd" to find out what is the current working directory. Then you can specify the correct location of your executable file.

Post by Elbert
I guess on multicore machines only one mpd daemon is started.

Yes.
Michael

Michael,

Thanks for suggesting. If I run the executable as "./pi" it runs only
a single process as MPI_COMM_SIZE returns 1. The location of the
executable is same as what "mpirun -np 4 pwd" returns.

I want to make a run with MPI_COMM_SIZE returning 4.

Elbert

[Michael Hofmann]

Post by Elbert
I want to make a run with MPI_COMM_SIZE returning 4.

Have you tried "mpirun -np 4 ./pi"?


Michael

[Elbert]

Post by Michael Hofmann

Post by Elbert
I want to make a run with MPI_COMM_SIZE returning 4.

Have you tried "mpirun -np 4 ./pi"?
Michael

Yes, I did and it works. The path of the executable needs to be
explicit.

Thanks,
Elbert