Hi Alaa,

Generally, for small number of processes, the performance of MPI_Bcast is usually equal to MPI_Isend/MPI_Recv, for large number of processes, broadcast should be better.

Could you please try the lateat version of MPICH on you system ? MPICH2 is very old. 

Please also give us following information.
Number of processes
Number of processes per node
The execution time of each algorithm

Min



Sent via my cell phone.


-------- Original message --------
From: alaa nashar <nashar_al@yahoo.com>
Date: 9/7/2016 7:04 AM (GMT-06:00)
To: discuss@mpich.org
Subject: [mpich-discuss] MPI_Send and MPI_Bcast

 Dear all
 
I have implemented the following two algorithms on my home Ethernet LAN containing 2/ and three heterogeneous devices using MPICH2.
 
Algorithm1:
1- Root process reads the contents of an input array.
2- It then sends the array data to all other processes.
3- All processes including the root process perform specific
   computations on their array copies.
4- Once the computations within each process are finished,
   the generated arrays are directly written by the process that
   performed the computations to separate files.
 
Algorithm2:
Same as Algorithm 1 except step 2 is replace by:
2- Root process broadcast the array data to all other processes.
 
The implementation of both algorithms  work fine and give the expected results but Algorithm2 that uses MIPI_Bcast is slower than Algorithm1 that uses MPI_Send
 
For my knowledge, MIPI_Bcast is faster than MPI_Send.
Please, would you guide me to know if there is any conflict of misunderstand.
 
Thanks a lot
 
Alaa