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Scatter

MPI_Scatter​

MPI_Scatter is a function through which one process divides an array into equal-sized chunks, where each chunk is sent, in order, to each process, including itself, within the communicator.

The function signature is as follows:

int MPI_Scatter(void* send_data, int send_count, MPI_Datatype send_datatype, void* recv_data, int recv_count, MPI_Datatype recv_datatype, int root, MPI_Comm communicator)

Where:

  • send_data (↓) - represents the data that is divided and sent to the processes within the communicator
  • send_count (↓) - represents the size of the chunk that each process receives (usually set as total_size / number_of_processes).
  • send_datatype (↓) - the data type of the data sent to processes
  • recv_data (↑) - represents the data that is received and stored by processes
  • recv_count (↓) - the size of the received data (usually total_size / number_of_processes)
  • recv_datatype (↓) - the data type received by processes (usually the same as send_datatype)
  • root (↓) - the identifier of the process that divides the data and sends it to the processes within the communicator, including itself
  • communicator (↓) - the communicator to which the processes belong (usually MPI_COMM_WORLD)

An illustration of how MPI_Scatter works:

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