Re: [OMPI users] Process 0 with different time executing the same code

There is nothing MPI specific in your code snippet. You should try to find out what is different in your code for node 0. You have mentioned that you have moved the root node to other nodes, so it's not machine specific. You might be setting up the arrays differently on the different nodes. You sh

Re: [OMPI users] Process 0 with different time executing the same code

Hi All, Thanks for the help. I think that I don't have the cache issue because all the processes have the same amount of data, and accessed in the same fashion. My problem is solved partially as I was using 2, 4, 8 , 16, 32 and 64 processes for my application code. Now what I did I used 3 pr

Re: [OMPI users] Process 0 with different time executing the same code

This is not an MPI problem. Without looking at your code in detail, I'm guessing that you're accessing memory without any regard to memory layout and/or caching. Such an access pattern will therefore thrash your L1 and L2 caches and access memory in a truly horrible pattern that guarantees

Re: [OMPI users] Process 0 with different time executing the same code

Thanks, The array bounds are the same on all the nodes and also the compute nodes are identical i.e. SunFire V890 nodes. And I have also changed the root process to be on different nodes, but the problem remains the same. I still dont understand the problem very well and my progress is in stand s

Re: [OMPI users] Process 0 with different time executing the same code

Thanks for your reply, I used MPI_Wtime for my application but even then process 0 took longer time executing the mentioned code segment. I might be worng, but what I see is process 0 takes more time to access the array elements than other processes. Now I dont see what to do because the mentione

Re: [OMPI users] Process 0 with different time executing the same code

HI I'm not sure if that is a problem, but in MPI applications you shoud use MPI_WTime() for time-measurements Jody On 10/25/07, 42af...@niit.edu.pk <42af...@niit.edu.pk> wrote: > Hi all, >I am a research assistant (RA) at NUST Pakistan in High Performance > Scientific Computing Lab. I am

[OMPI users] Process 0 with different time executing the same code

Hi all, I am a research assistant (RA) at NUST Pakistan in High Performance Scientific Computing Lab. I am working on the parallel implementation of the Finitie Difference Time Domain (FDTD) method using MPI. I am using the OpenMPI environment on a cluster of 4 SunFire v890 cluster connected