[mpich-discuss] Error: "MPIR_Get_contextid_sparse_group(1193): Too many communicators (0/2048)"

[Rajeev Thakur]

> What do you mean with: "Why can’t all processes open one large window?" I guess I miss something.

If each process has an array of objects that belong to it (called array A say) , then with a single call to MPI_Win_create you can create a window object that has everyone's A arrays in it.

Rajeev



On May 22, 2014, at 9:46 AM, Ted Sariyski <tsariysk at craft-tech.com> wrote:

> It is about MPI_win. Here is the problem as it relates to MPI (it is a Boltzmann type equation).
> 
> There are N particles interacting with each other. Interaction is directional, so that a particle interacts only with those particles, which are within a narrow cone. The first step is to segregate the initial set of N particles into subsets of particles  (I called it 'objects'),  which interact with each other. Here is what I do:
> 	• Assign each object to a process.
> 	• The process which owns a object:
> 		• Makes a guess for the maximum number of particles expected in this object.
> 		• Allocates memory for it.
> 		• Opens a shared window.
> 	• All processes
> 		• Each particle identify which object it belongs to, and PUTs its data there. 
> 	• After assembly is done, objects are passed to a solver.
> 	• Repeat
> What do you mean with: "Why can’t all processes open one large window?" I guess I miss something. 
> Thanks,
> --Ted
> 
> 
> On 05/21/2014 11:03 PM, Balaji, Pavan wrote:
>> On May 21, 2014, at 6:02 PM, Ted Sariyski <tsariysk at craft-tech.com>
>>  wrote:
>> 
>>> Memory limitations. With one large window all processes have to allocate memory for the objects they own as well as for objects assigned to other process.
>>> 
>> Are we talking about the same thing here?  I’m referring to an MPI_Win.  What objects do processes need to keep track of?
>> 
>>   — Pavan
>> 
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