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# http://mvapich.cse.ohio-state.edu/benchmarks/
from libmpi import ffi, lib
def osu_latency(
BENCHMARH="MPI Latency Test",
skip=1000,
loop=10000,
skip_large=10,
loop_large=100,
large_message_size=8192,
MAX_MSG_SIZE=1 << 22,
):
myid = ffi.new("int*")
numprocs = ffi.new("int*")
lib.MPI_Comm_rank(lib.MPI_COMM_WORLD, myid)
lib.MPI_Comm_size(lib.MPI_COMM_WORLD, numprocs)
myid = myid[0]
numprocs = numprocs[0]
if numprocs != 2:
if myid == 0:
errmsg = "This test requires exactly two processes"
else:
errmsg = None
raise SystemExit(errmsg)
sbuf = ffi.new("unsigned char[]", MAX_MSG_SIZE)
rbuf = ffi.new("unsigned char[]", MAX_MSG_SIZE)
dtype = lib.MPI_BYTE
tag = 1
comm = lib.MPI_COMM_WORLD
status = lib.MPI_STATUS_IGNORE
if myid == 0:
print(f"# {BENCHMARH}")
if myid == 0:
print(f"# {'Size [B]':<8s}{'Latency [us]':>20s}")
message_sizes = [0] + [2**i for i in range(30)]
for size in message_sizes:
if size > MAX_MSG_SIZE:
break
if size > large_message_size:
skip = skip_large
loop = loop_large
iterations = list(range(loop + skip))
#
lib.MPI_Barrier(comm)
if myid == 0:
for i in iterations:
if i == skip:
t_start = lib.MPI_Wtime()
lib.MPI_Send(sbuf, size, dtype, 1, tag, comm)
lib.MPI_Recv(rbuf, size, dtype, 1, tag, comm, status)
t_end = lib.MPI_Wtime()
elif myid == 1:
for i in iterations:
if i == skip:
pass
lib.MPI_Recv(rbuf, size, dtype, 0, tag, comm, status)
lib.MPI_Send(sbuf, size, dtype, 0, tag, comm)
#
if myid == 0:
latency = (t_end - t_start) * 1e6 / (2 * loop)
print(f"{size:-10d}{latency:20.2f}")
def main():
lib.MPI_Init(ffi.NULL, ffi.NULL)
osu_latency()
lib.MPI_Finalize()
if __name__ == "__main__":
main()
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