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from libmpi import ffi, lib
def ring(comm, count=1, loop=1, skip=0):
size_p = ffi.new('int*')
rank_p = ffi.new('int*')
lib.MPI_Comm_size(comm, size_p)
lib.MPI_Comm_rank(comm, rank_p)
size = size_p[0]
rank = rank_p[0]
source = (rank - 1) % size
dest = (rank + 1) % size
sbuf = ffi.new('unsigned char[]', [42]*count)
rbuf = ffi.new('unsigned char[]', [ 0]*count)
iterations = list(range((loop+skip)))
if size == 1:
for i in iterations:
if i == skip:
tic = lib.MPI_Wtime()
lib.MPI_Sendrecv(sbuf, count, lib.MPI_BYTE, dest, 0,
rbuf, count, lib.MPI_BYTE, source, 0,
comm, lib.MPI_STATUS_IGNORE)
else:
if rank == 0:
for i in iterations:
if i == skip:
tic = lib.MPI_Wtime()
lib.MPI_Send(sbuf, count, lib.MPI_BYTE, dest, 0, comm)
lib.MPI_Recv(rbuf, count, lib.MPI_BYTE, source, 0, comm, lib.MPI_STATUS_IGNORE)
else:
sbuf = rbuf
for i in iterations:
if i == skip:
tic = lib.MPI_Wtime()
lib.MPI_Recv(rbuf, count, lib.MPI_BYTE, source, 0, comm, lib.MPI_STATUS_IGNORE)
lib.MPI_Send(sbuf, count, lib.MPI_BYTE, dest, 0, comm)
toc = lib.MPI_Wtime()
if rank == 0 and ffi.string(sbuf) != ffi.string(rbuf):
import warnings, traceback
try:
warnings.warn("received message does not match!")
except UserWarning:
traceback.print_exc()
lib.MPI_Abort(comm, 2)
return toc - tic
def ringtest(comm):
size = ( 1 )
loop = ( 1 )
skip = ( 0 )
lib.MPI_Barrier(comm)
elapsed = ring(comm, size, loop, skip)
size_p = ffi.new('int*')
rank_p = ffi.new('int*')
lib.MPI_Comm_size(comm, size_p)
lib.MPI_Comm_rank(comm, rank_p)
comm_size = size_p[0]
comm_rank = rank_p[0]
if comm_rank == 0:
print ("time for %d loops = %g seconds (%d processes, %d bytes)"
% (loop, elapsed, comm_size, size))
def main():
lib.MPI_Init(ffi.NULL, ffi.NULL)
ringtest(lib.MPI_COMM_WORLD)
lib.MPI_Finalize()
if __name__ == '__main__':
main()
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