hyPACK-2013 Mode 1 : MPI 1.X Collective Comm. & Comp. MPI Lib. Calls

Module 2 : MPI programs using Collective communication and Computation library calls and execute on Message Passing Cluster or Multi Core Systems that support MPI library.

Write MPI program to broadcast message "Hello world" to all the process .

Write MPI program to scatter n integers on p processes (Assume that n is divisible by p ) .

Write MPI Program to gather unequal number of intergers from each process and obtain the resultant data on the process with rank 0. (Assume that the each process has unequal number of integers.)

Write MPI Program to gather n intgers from each process and obtain the resultant data on each process.

Write MPI Program to perform all-to-all communication of n integers on p process. (Assume that the each process has n integers where n is divisible by p ).

Write MPI Program to compute the sum of q on p process and proces with rank 0 prints the resultant sum. (Assume that the each process has q integers where q is equal to n/p and n is total number of integers on each process).

Write MPI program to compute the sum of q integers on p process and each process prints the resultant sum. (Assume that the each process has q integers and q is equal to n/p and n is total numbe rof integers)

Write MPI Program to compute the funciton pi using MPI collective communication and computation library calls.

Objective

Write a MPI program to braodcast an integer array A of dimension n on p processors of cluster using MPI_Broadcast   communication library call.

Description

Process with rank 0 genrates an integer array A of size 24 and braodcast the array to all the process.

Input

Process with rank 0 reads the input data.You have to adhere strictly the following format for the input file.
#Line 1 : Size of the array
#Line 2 : data in order, this means that the data of second entry of the input array A follows the

first and so on. 

24 
2  10  3  4  23  14  4  6  8  32 63  86  12  8  3  9  13  4  14  16  18  2  9  86 

Output 

Each process prints its own n elements of array A.

Objective

Write a MPI program to scatter an integer array A of dimension n on p processors of IBM AIX cluster using MPI_Scatter  communication library calls.

Description

Assume thatn is multiple of p and index of the array A starts from 0 (as in C-Program).  Processor with rank k, k = 0,1, ..., p-1 gets n/p values starting from A[i], i = k*n/p to (k+1)*n/p - 1.

Figure 4 Process p0 performing MPI_Scatter Collective Communication Primitive 

Input

Process with rank 0 reads the input data.You have to adhere strictly the following format for the input file.

#Line 1 : Size of the array
#Line 2 : data in order, this means that the data of second entry of the input array A follows the

first and so on. 

24 
2  10  3  4  23  14  4  6  8  32 63  86  12  8  3  9  13  4  14  16  18  2  9  86 

Output 

Each process prints its own n/p elements of array A.  

Objective

Write a MPI program to gather unequal integer array values from each process and store the output values in the global integer array A of dimension n on p process on a message passing cluster. Use MPI_gatherv  Communication library call in theprogram.  

Description :

Each process reads respective input array of different size n/p from the given input file. The process wit rank 0 accumalates the total number of integers to be recevied from the each process and allocates memory for the output integer array and performs MPI_gatherv operation.

Input

Each process k reads the input file.You have to adhere strictly the following format for the input file. 
#Line 1 : Size of the local array 
#Line 2 : data in order, this means that the data of second entry of the input array A follows the first and so on. 
A sample input file is given below. User can create his own input files in this format.
Input file for process with rank 0  
8
2 4 8 16 32 64 128 256  

Each process with rank greater than 0 reades the Input file with differnt total number of integers. You have to adhere strictly the same format for the input file as given above.

Output 

Each process prints the output array A.

Objective

Write a MPI program to gather values from each process and store the output values in the global integer array A of dimension n on p process of cluster. Use MPI_Allgather  Communication library call in theprogram.  

Description

Assume n be the dimension of an integer input array A , output array B , and p be the processes used in the parallel program. the integer array A [i] of size n/p with known n/p values where varies from 0 to n/p - 1 is given as additional input on processor with rank k  (k = 0,1, ... p-1). Each process reads respective input array of size n/p from the given input file. You have to adhere strictly the following format for the input file. 

Figure 5  MPI_Allgather Collective Communication Primitive

Input

Each process k reads the input file.You have to adhere strictly the following format for the input file. 
#Line 1 : Size of the local array 
#Line 2 : data in order, this means that the data of second entry of the input array A follows the
first and so on. 

A sample input file is given below.

Input file for process 0 
6 
21 18 54 24 33 69 
 

• Output 

  Each process prints the output array A. 
   

Objective

Write a MPI program to gather values from each process and store the output values in the global integer array A of dimension n on p process of cluster. Use MPI_AllgatherCommunication library call in the program.

Description

Assume n be the dimension of an integer input array A , output array B , and p be the processes used in the parallel program. Each process reads input integer array of size n from the given input file. Assume that n is divisible by p

Figure 5  MPI_Alltoall Collective Communication Primitive

Input

Each process k reads the input file.You have to adhere strictly the following format for the input file.

#Line 1 : Size of the local array 
#Line 2 : data in order, this means that the data of second entry of the input array A follows the
first and so on. 
A sample input file is given below. For convenience sake, 4 processes are used in this example.

Input file for process 0 
16  
21 6 8 45 54 24 33 72 84 12 25 31 46 16 94 65

Output 

Each process prints the output array B.

Objective

Write a MPI program to find sum of q integers, on p processors of mesaage passing cluster, using MPI collective communication and computation library call. 

Description

MPI collective communication and computation library call, MPI_Reduce is used.

Input

For input data, let each process use its identifying number, i.e. the value of its rank. For example, process with rank 0 uses the input integer r 0, process with rank 1 uses the input integer number 1, etc.

Output

Process wih rank 0 prints the final sum.

Objective

Write a MPI program to find sum of q integers, on p processors of mesaage passing cluster, using MPI collective communication and computation library call. 

Description

In this example MPI collective communication and computation library call, MPI_Allreduce is used.

Input

For input data, let each process use its identifying number, i.e. the value of its rank. For example, process with rank 0 uses the input intger r 0, process with rank 1 uses the input integer number 1, etc.

Output

Each process prints the final sum.

Objective

Write a MPI program to compute the value of pi function by numerical integration of a function f(x) = 4/(1+x ² ) between the limits 0 and 1.

Description

There are several approaches to parallelizing a serial program. One approach is to partition the data among the processes. That is we partition the interval of integration [0,1] among the processes, and each process estimates local integral over its own subinterval. The local calculations produced by the individual processes are combined to produce the final result. Each process sends its integral to process 0, which adds them and prints the result.

To perform this integration numerically, divide the interval from 0 to 1 into n subintervals and add up the areas of the rectangles as shown in the Figure 3 (n = 5). Large values of n give more accurate approximations of pi . Use MPI Collective communication library calls.

Figure 3 Numerical integration of pie function

We assume that n is total number of subintervals, p is the number of processes and p < n. One simple way to distribute the total number of subintervals to each process is to dividen by p. There are two kinds of mappings that balance the load. One is a block mapping, partitions the array elements into blocks of consecutive entries and assigns the block to the processes. The other mapping is a cyclic mapping. It assigns the first element to the first process, the second element to the second, and so on. If n > p, we get back to the first process, and repeat the assignment process for remaining elements. This process is repeated until all the elements are assigned. We have used a cyclic mapping for partition of interval [0,1] onto p processes.

Input

Process with rank 0 reads the input parameter n, the number of intervals as commandline arguement

Output

Process with rank 0 prints the computed value of pi function.