From 711905aa4a03c1b755be397fca52dadba9786be4 Mon Sep 17 00:00:00 2001
From: Christopher Wood <cjwood@us.ibm.com>
Date: Sat, 26 Sep 2020 15:42:32 -0400
Subject: [PATCH] Add AerProvider function for optimizing backend options

---
 qiskit/providers/aer/aerprovider.py         |  9 +++++++++
 qiskit/providers/aer/backends/aerbackend.py | 16 ++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/qiskit/providers/aer/aerprovider.py b/qiskit/providers/aer/aerprovider.py
index 2fdba50080..305bd51a13 100644
--- a/qiskit/providers/aer/aerprovider.py
+++ b/qiskit/providers/aer/aerprovider.py
@@ -17,6 +17,8 @@
 from qiskit.providers import BaseProvider
 from qiskit.providers.providerutils import filter_backends
 
+from .aererror import AerError
+from .backends.aerbackend import AerBackend
 from .backends.qasm_simulator import QasmSimulator
 from .backends.statevector_simulator import StatevectorSimulator
 from .backends.unitary_simulator import UnitarySimulator
@@ -48,3 +50,10 @@ def backends(self, name=None, filters=None, **kwargs):
 
     def __str__(self):
         return 'AerProvider'
+
+    @staticmethod
+    def optimize_backend_options(min_qubits=10, max_qubits=20, ntrials=10):
+        """Set optimal OpenMP and fusion options for backend."""
+        from .profile import optimize_backend_options
+        return optimize_backend_options(
+            min_qubits=min_qubits, max_qubits=max_qubits, ntrials=ntrials)
diff --git a/qiskit/providers/aer/backends/aerbackend.py b/qiskit/providers/aer/backends/aerbackend.py
index ae467f8bf1..c3abcc6069 100644
--- a/qiskit/providers/aer/backends/aerbackend.py
+++ b/qiskit/providers/aer/backends/aerbackend.py
@@ -139,9 +139,25 @@ def _format_qobj(self, qobj, backend_options, noise_model):
         output = qobj.to_dict()
         # Add new parameters to config from backend options
         config = output["config"]
+
         if backend_options is not None:
             for key, val in backend_options.items():
                 config[key] = val if not hasattr(val, 'to_dict') else val.to_dict()
+
+        # Add default OpenMP options
+        if 'statevector_parallel_threshold' not in config and hasattr(
+                self, '_statevector_parallel_threshold'):
+            config['statevector_parallel_threshold'] = self._statevector_parallel_threshold
+
+        # Add default fusion options
+        if 'fusion_threshold' not in config:
+            if 'gpu' in config.get('method', '') and hasattr(self, '_fusion_threshold_gpu'):
+                # Set GPU fusion threshold
+                config['fusion_threshold'] = self._fusion_threshold_gpu
+            elif hasattr(self, '_fusion_threshold'):
+                # Set CPU fusion threshold
+                config['fusion_threshold'] = self._fusion_threshold
+
         # Add noise model to config
         if noise_model is not None:
             config["noise_model"] = noise_model