Add support for x0 with skopt search strategy

Author: stijnh

kernel_tuner/strategies/skopt.py

@@ -32,7 +32,6 @@ def tune(searchspace: Searchspace, runner, tuning_options):
     max_fevals = min(tuning_options.get("max_fevals", np.inf), searchspace.size)
 
     # Const function
-    cost_func = CostFunc(searchspace, tuning_options, runner)
     opt_config, opt_result = None, None
 
     # The dimensions. Parameters with one value become categorical
@@ -76,6 +75,14 @@ def tune(searchspace: Searchspace, runner, tuning_options):
     if tuning_options.verbose:
         print(f"Asked optimizer for {num_initial} points: {batch}")
 
+    # Create cost function
+    cost_func = CostFunc(searchspace, tuning_options, runner)
+    x0 = costfunc.get_start_pos()
+
+    # Add x0 if the user has requested it
+    if x0 is not None:
+        batch.insert(0, x0)
+
     try:
         while eval_count < max_fevals:
             if not batch: