How to calculate the runtime of MPI program in mpi4py - mpi

Question

I wrote this code and tried some functions to calculate the time but it shows an error while running.I tried to use the C functions that is used to calculate runtime of each processor by using Wtime() and MPI_Reduce.Wtime() works I guess but the reduce function does not work the way it should.
The code is
from mpi4py import MPI
import mpi4py
import numpy as np
comm = MPI.COMM_WORLD
size = comm.size
rank = comm.Get_rank()
time1 = mpi4py.MPI.Wtime()
a = np.random.randint(10, size=(10, 10))
if rank == 0:
b = np.random.randint(10, size=(10, 10))
print(b)
else:
b = None
b = comm.bcast(b, root=0)
c = np.dot(a, b)
if size == 1:
result = np.dot(a, b)
else:
if rank == 0:
a_row = a.shape[0]
if a_row >= size:
split = np.array_split(a, size, axis=0)
else:
split = None
split = comm.scatter(split, root=0)
split = np.dot(split, b)
data = comm.gather(split, root=0)
time2 = mpi4py.MPI.Wtime()
duration = time2 - time1
totaltime = comm.reduce(duration,op = sum, root = 0)
print("Runtime at %d is %f" %(rank,duration))
if rank == 0:
result = np.vstack(data)
print(result)
print(totaltime)
The error it shows is
Runtime at 3 is 0.000574
Traceback (most recent call last):
File "matrixmultMPI.py", line 48, in <module>
totaltime = comm.reduce(duration,op = sum, root = 0)
File "mpi4py/MPI/Comm.pyx", line 1613, in mpi4py.MPI.Comm.reduce
File "mpi4py/MPI/msgpickle.pxi", line 1322, in mpi4py.MPI.PyMPI_reduce
File "mpi4py/MPI/msgpickle.pxi", line 1254, in mpi4py.MPI.PyMPI_reduce_intra
File "mpi4py/MPI/msgpickle.pxi", line 1126, in mpi4py.MPI.PyMPI_reduce_p2p
TypeError: 'float' object is not iterable
Traceback (most recent call last):
File "matrixmultMPI.py", line 48, in <module>
totaltime = comm.reduce(duration,op = sum, root = 0)
File "mpi4py/MPI/Comm.pyx", line 1613, in mpi4py.MPI.Comm.reduce
File "mpi4py/MPI/msgpickle.pxi", line 1322, in mpi4py.MPI.PyMPI_reduce
File "mpi4py/MPI/msgpickle.pxi", line 1254, in mpi4py.MPI.PyMPI_reduce_intra
File "mpi4py/MPI/msgpickle.pxi", line 1126, in mpi4py.MPI.PyMPI_reduce_p2p
TypeError: 'float' object is not iterable
Traceback (most recent call last):
File "matrixmultMPI.py", line 48, in <module>
totaltime = comm.reduce(duration,op = sum, root = 0)
File "mpi4py/MPI/Comm.pyx", line 1613, in mpi4py.MPI.Comm.reduce
File "mpi4py/MPI/msgpickle.pxi", line 1322, in mpi4py.MPI.PyMPI_reduce
File "mpi4py/MPI/msgpickle.pxi", line 1254, in mpi4py.MPI.PyMPI_reduce_intra
File "mpi4py/MPI/msgpickle.pxi", line 1126, in mpi4py.MPI.PyMPI_reduce_p2p
TypeError: 'float' object is not iterable
What's wrong with it and how do I go about it!!?