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<DIV>Hi, Huiwei, </DIV>
<DIV> I think the best solution for your
question is cuting the data buffers into smaller sizes. However,
This may be not easy. </DIV>
<DIV> According to my
experience, the suggestions are </DIV>
<DIV> 1. Do
not use MPI_Alltoallv, and use nonblocking communication insted, such
as MPI_send and MPI_irecv. </DIV>
<DIV> 2. In
solution 1, each data buffer can not exceeds 2GB too, If
the data is too large, I think we should develop a
class encapsulated with the data buffer cuting method.</DIV>
<DIV> </DIV>
<DIV> However, using int as the
parameters' type in MPI communication primitives is not reasonable. As we
know, in x86_64 machine, sizeof(int)=4, however sizeof(long) and
sizeof(long long int)=8, we should support the new parameter type of long
and long long int. </DIV>
<DIV> </DIV>
<HR style="WIDTH: 210px; HEIGHT: 1px" align=left color=#b5c4df SIZE=1>
<DIV><SPAN>jt.meng</SPAN></DIV>
<DIV> </DIV>
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<DIV><B>From:</B> <A href="mailto:huiweilu@mcs.anl.gov">Huiwei Lu</A></DIV>
<DIV><B>Date:</B> 2013-12-14 07:18</DIV>
<DIV><B>To:</B> <A href="mailto:discuss@mpich.org">discuss</A></DIV>
<DIV><B>Subject:</B> [mpich-discuss] The max amount of data each process
can send in MPI_Alltoallv</DIV></DIV></DIV>
<DIV>
<DIV style="BACKGROUND-COLOR: white" class=FoxDiv20131214120922199808>Hi, folks,
<DIV><BR></DIV>
<DIV>What’s the max amount of data each process can send in MPI_Alltoallv? <A
href="http://www.mcs.anl.gov/research/projects/mpi/www/www3/MPI_Alltoallv.html">http://www.mcs.anl.gov/research/projects/mpi/www/www3/MPI_Alltoallv.html</A></DIV>
<DIV><BR></DIV>
<DIV>As I understand, the input parameter of <I>sendcnts</I> is an array of int,
so the amount of data each process can send is limited to MAX_INT (approximately
2G).</DIV>
<DIV><BR></DIV>
<DIV>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.</DIV>
<DIV><BR></DIV>
<DIV>Thanks.</DIV>
<DIV>--</DIV>
<DIV>Huiwei Lu<BR><A
href="http://www.mcs.anl.gov/~huiweilu/">http://www.mcs.anl.gov/~huiweilu/</A></DIV></DIV></DIV></BODY></HTML>