Thank you for your tips, Rajeev, Jeff and JT, I used Rajeev’s suggestion to send about 4GB data (100M items) per process, and it works fine. @JT, yes, if the data continue to grow and there is no proper way to do it in MPI type, I will have to partition the buffer to smaller trunks. Thanks again for your help. — Huiwei On Dec 13, 2013, at 7:02 PM, Rajeev Thakur <[email protected]> wrote:

You can create a contiguous datatype of size 1GB and then send 1G items of that size :-).

On Dec 13, 2013, at 5:18 PM, Huiwei Lu <[email protected]> wrote:

...

Hi, folks,

What’s the max amount of data each process can send in MPI_Alltoallv? http://www.mcs.anl.gov/research/projects/mpi/www/www3/MPI_Alltoallv.html

As I understand, the input parameter of sendcnts is an array of int, so the amount of data each process can send is limited to MAX_INT (approximately 2G).

What if I want to use MPI_Alltoallv-like MPI routines to send a buffer of data that exceeds 2GB? Does it need to cut the data buffers to smaller sizes? Is there an easy way to do this? The reason I am asking is one of my distributed sort algorithm uses MPI_Alltoallv to distribute data after partitioning; it crashed when I tried to send in each process more than 2GB data.

Thanks. -- Huiwei Lu http://www.mcs.anl.gov/~huiweilu/ _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss

_______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss