WRF IO Quilting
=====================

* Two types	of MPI tasks: compute (client) and I/O (server)

* Compute tasks:

    - Total	number = nproc_x*nproc_y (number of processors along X and y axes for decomposion)	
    - First	number is zero
    
* I/O tasks:

    - Total	number = nio_groups*nio_tasks_per_group
    - Nio_tasks_per_group cannot exceed	nproc_y
    - First	I/O	task number	immediately	follows	last compute task number	

* Code will	attempt	to match each I/O task with	compute	tasks in east-west rows

    - Ideally nproc_y should be	exact multiple of nio_tasks_per_group

.. figure:: ioquilting.PNG
    :scale: 50%
    :align: center