Print runtime of an optimizer

Question

I want to find the runtime of my program, i.e. the time it is in the quantum computer without queue time. However, I am using an optimizer so the code is a little different.

from qiskit.utils import algorithm_globals




algorithm_globals.random_seed = 1234
backend = provider.get_backend('ibmq_belem')

#backend = Aer.get_backend('statevector_simulator')

cobyla = COBYLA()
cobyla.set_options(maxiter=1)
ry = TwoLocal(num_assets, 'ry', 'cz', reps=3, entanglement='full')
quantum_instance = QuantumInstance(backend=backend, seed_simulator=seed, seed_transpiler=seed)
vqe_mes = VQE(ry, optimizer=cobyla, quantum_instance=quantum_instance)
vqe = MinimumEigenOptimizer(vqe_mes)
result = vqe.solve(qp)



print(result)
#print_result(result)

How do I figure out the runtime? Printing result only shows

optimal function value: -0.01488461311339271
optimal value: [1. 0. 0. 1.]
status: SUCCESS

Answer 1

I made a start and end_operation point with the method now(). At the end of the operation it will display the time it needed:

from qiskit.utils import algorithm_globals
from time import time as now



algorithm_globals.random_seed = 1234
backend = provider.get_backend('ibmq_belem')

#backend = Aer.get_backend('statevector_simulator')

cobyla = COBYLA()
cobyla.set_options(maxiter=1)
ry = TwoLocal(num_assets, 'ry', 'cz', reps=3, entanglement='full')
quantum_instance = QuantumInstance(backend=backend, seed_simulator=seed, seed_transpiler=seed)
start_operation = now()
vqe_mes = VQE(ry, optimizer=cobyla, quantum_instance=quantum_instance)
vqe = MinimumEigenOptimizer(vqe_mes)
end_operation = now()
result = vqe.solve(qp)

    
    process_time = (
end_operation - start_operation
)
print(f"Operation took {process_time:.2f} seconds in machine")



print(result)
#print_result(result)

---

Another possibility to meassure the program is to use the command rep_time:

rep_time (int) – Time per program execution in seconds. Must be from the list provided by the backend (backend.configuration().rep_times). Defaults to the first entry.

In your specific case you need to add it in your code like this:

...
quantum_instance = QuantumInstance(backend=backend, rep_time=rep_time, seed_simulator=seed, seed_transpiler=seed)
...