What wrong with only allowing the rank 0 to execute the code before and after
the funcCompScalapack function as indicated in the example below:
int main()
{
//Initialize MPI
MPI_Init(NULL,NULL);
MPI_Comm_rank(MPI_COMM_WORLD, &myrank);
if( 0 == rank ) {
//some work that must be done by only one node
…..
}
//function that runs internally some scalapack computations
funcCompScalapack();
if( 0 == my rank ) {
//other work must be done by the original node
….
}
//finalize MPI
MPI_Finalize();
return 0;
}
void funcCompScalapack()
{
//here I think I should write some code in order to inform that the work
must be done by a number X or processors
//maybe using MPI_Comm_spawn?
....
//some BLACS and ScaLAPACK computations
....
return;
}
George.
On Jun 6, 2013, at 18:43 , Ralph Castain <r...@open-mpi.org> wrote:
> I honestly don't know - you'd have to look at the PVM docs. You also might
> look at OpenMP and try doing it with multiple threads instead of processes,
> though that limits you to running on a single node.
>
> On Jun 6, 2013, at 9:37 AM, José Luis García Pallero <jgpall...@gmail.com>
> wrote:
>
>> 2013/6/6 Ralph Castain <r...@open-mpi.org>
>>
>> On Jun 6, 2013, at 8:58 AM, José Luis García Pallero <jgpall...@gmail.com>
>> wrote:
>>
>>> 2013/6/6 Ralph Castain <r...@open-mpi.org>
>>> should work!
>>>
>>> Thank you for your answer.
>>>
>>> So I understand that MPI_Comm_spawn() is my function. But I see in the
>>> documentation that the first argument is char* command, and command is the
>>> name of the program to spawn, but I not want to execute an external
>>> program. Only a piece of code in the same program. How can I deal with that.
>>
>> You'll have to move that code into a separate program, then pass any data it
>> requires using MPI_Send/receive or a collective operation
>>
>> Mmm... bad news. It is impossible, then in MPI. I need all the code in the
>> same executable.
>>
>> I know this is offtopic in this list, but, can I perform the calculations as
>> I want using PVM? (ScaLAPACK et al. can also run with PVM)
>>
>> Cheers
>>
>>
>>> The second argument is char* argv[]. Admits MPI_Comm_spawn() the NULL value
>>> for argv[], as MPI_Init()?
>>>
>>> I know also that I can do my program by putting the code before and after
>>> the call funcCompScalapack() into an if() checking if the node is the root
>>> and then these pieces of code will be executed only by the root. But I want
>>> to maintain all the program free of MPI code except the funcCompScalapack()
>>> function
>>>
>>> Cheers
>>>
>>> On Jun 6, 2013, at 8:24 AM, José Luis García Pallero <jgpall...@gmail.com>
>>> wrote:
>>>
>>>> 2013/6/6 Ralph Castain <r...@open-mpi.org>
>>>> Afraid not. You could start a single process, and then have that process
>>>> call MPI_Comm_spawn to launch the rest of them
>>>>
>>>> Mmmm... sounds good
>>>>
>>>> I'm writing an example program using ScaLAPACK. I have written the
>>>> ScaLAPACK code in an independent function that must be called after some
>>>> work in an individual node (the root one). So I need the first part of the
>>>> program be executed by one process. My example looks like:
>>>>
>>>> int main()
>>>> {
>>>> //some work that must be done by only one node
>>>> .....
>>>> //function that runs internally some scalapack computations
>>>> funcCompScalapack();
>>>> //other work must be done by the original node
>>>> ....
>>>> return 0;
>>>> }
>>>>
>>>> void funcCompScalapack()
>>>> {
>>>> //Initialize MPI
>>>> MPI_Init(NULL,NULL);
>>>> //here I think I should write some code in order to inform that the
>>>> work must be done by a number X or processors
>>>> //maybe using MPI_Comm_spawn?
>>>> ....
>>>> //some BLACS and ScaLAPACK computations
>>>> ....
>>>> //finalize MPI
>>>> MPI_Finalize();
>>>> return;
>>>> }
>>>>
>>>> When I execute this program as mpirun -np X myprogram, the pieces of code
>>>> before and after the call to function funcCompScalapack() are executed by
>>>> X nodes, but these orders must be executed only by one. So my idea is to
>>>> execute the binary as ./myprogram (the same I think as mpirun -np 1
>>>> myprogram) and internally set the number of processes in
>>>> funcCompScalapack() after the MPI_Init() call.
>>>>
>>>> Is my idea possible?
>>>>
>>>> Thanks
>>>>
>>>>
>>>> On Jun 6, 2013, at 7:54 AM, José Luis García Pallero <jgpall...@gmail.com>
>>>> wrote:
>>>>
>>>>> Hello:
>>>>>
>>>>> I'm newbie in the use of MPI, so probably I ask some stupid question (or
>>>>> previously asked, but in this case I have searched in the archive and I
>>>>> haven't found anything):
>>>>>
>>>>> Exists any other way than -np X in order to pass the number of processes
>>>>> to start for an MPI program? I mean a function of the style
>>>>> MPI_Set_Number_Processes() or similar
>>>>>
>>>>> Thanks
>>>>>
>>>>> --
>>>>> *****************************************
>>>>> José Luis García Pallero
>>>>> jgpall...@gmail.com
>>>>> (o<
>>>>> / / \
>>>>> V_/_
>>>>> Use Debian GNU/Linux and enjoy!
>>>>> *****************************************
>>>>> _______________________________________________
>>>>> users mailing list
>>>>> us...@open-mpi.org
>>>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>>>
>>>>
>>>> _______________________________________________
>>>> users mailing list
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>>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>>>
>>>>
>>>>
>>>> --
>>>> *****************************************
>>>> José Luis García Pallero
>>>> jgpall...@gmail.com
>>>> (o<
>>>> / / \
>>>> V_/_
>>>> Use Debian GNU/Linux and enjoy!
>>>> *****************************************
>>>> _______________________________________________
>>>> users mailing list
>>>> us...@open-mpi.org
>>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>>
>>>
>>> _______________________________________________
>>> users mailing list
>>> us...@open-mpi.org
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>>>
>>>
>>>
>>> --
>>> *****************************************
>>> José Luis García Pallero
>>> jgpall...@gmail.com
>>> (o<
>>> / / \
>>> V_/_
>>> Use Debian GNU/Linux and enjoy!
>>> *****************************************
>>> _______________________________________________
>>> users mailing list
>>> us...@open-mpi.org
>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>
>>
>> _______________________________________________
>> users mailing list
>> us...@open-mpi.org
>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>
>>
>>
>> --
>> *****************************************
>> José Luis García Pallero
>> jgpall...@gmail.com
>> (o<
>> / / \
>> V_/_
>> Use Debian GNU/Linux and enjoy!
>> *****************************************
>> _______________________________________________
>> users mailing list
>> us...@open-mpi.org
>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>
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> users mailing list
> us...@open-mpi.org
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