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 <[email protected]> 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 <[email protected]> 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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