Sorry; traveling and didn't see the whole thread. - Eric On Wednesday, July 27, 2016, Eric A. Borisch <[email protected]> wrote:
This might be the struct alignment bug I tracked down a few months ago? (Alignment attribute in the wrong place.)
On Tuesday, July 26, 2016, Andreas Noack <[email protected] <javascript:_e(%7B%7D,'cvml','[email protected]');>> wrote:
On my El Capitan macbook I get a segfault when running the program below with more than a single process but only when MPICH has been compiled with Clang.
I don't get that good debug info but here is some of what I got
(lldb) c Process 61129 resuming Process 61129 stopped * thread #1: tid = 0x32c438, 0x00000003119d0432 libpmpi.12.dylib`MPID_Request_create + 244, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=EXC_I386_GPFLT) frame #0: 0x00000003119d0432 libpmpi.12.dylib`MPID_Request_create + 244 libpmpi.12.dylib`MPID_Request_create: -> 0x3119d0432 <+244>: movaps %xmm0, 0x230(%rax) 0x3119d0439 <+251>: movq $0x0, 0x240(%rax) 0x3119d0444 <+262>: movl %ecx, 0x210(%rax) 0x3119d044a <+268>: popq %rbp
My version of Clang is
Apple LLVM version 7.3.0 (clang-703.0.31) Target: x86_64-apple-darwin15.6.0 Thread model: posix InstalledDir: /Library/Developer/CommandLineTools/usr/bin
and the bug has been confirmed by my colleague who is running Linux and compiling with Clang 3.8. The program runs fine with OpenMPI+Clang.
#include <mpi.h> #include <stdio.h> #include <stdlib.h>
int main(int argc, char *argv[]) { MPI_Init(&argc, &argv);
MPI_Comm comm = MPI_COMM_WORLD; uint64_t *A, *C; int rnk;
MPI_Comm_rank(comm, &rnk); A = calloc(1, sizeof(uint64_t)); C = calloc(2, sizeof(uint64_t)); A[0] = rnk + 1;
MPI_Allgather(A, 1, MPI_UINT64_T, C, 1, MPI_UINT64_T, comm);
MPI_Finalize(); return 0; }
Best regards
Andreas Noack Postdoctoral Associate Computer Science and Artificial Intelligence Laboratory Massachusetts Institute of Technology
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