Improvements to the stop criterion and cost function return values

Author: fjwillemsen

kernel_tuner/strategies/common.py

@@ -180,7 +180,8 @@ def __call__(self, x, check_restrictions=True):
             return_value = result[self.tuning_options.objective]
         else:
             return_value = result[self.tuning_options.objective] or sys.float_info.max
-        return_value = -return_value if self.tuning_options.objective_higher_is_better else return_value
+        if not isinstance(return_value, util.ErrorConfig):
+            return_value = -return_value if self.tuning_options.objective_higher_is_better else return_value
 
         # include raw data in return if requested
         if self.return_raw is not None:

kernel_tuner/util.py

@@ -205,7 +205,8 @@ def check_stop_criterion(to: dict) -> float:
     if "max_fevals" in to:
         if len(to.unique_results) >= to.max_fevals:
             raise StopCriterionReached(f"max_fevals ({to.max_fevals}) reached")
-        return len(to.unique_results) / to.max_fevals
+        if not "time_limit" in to:
+            return len(to.unique_results) / to.max_fevals
     if "time_limit" in to:
         time_spent = (time.perf_counter() - to.start_time) + (to.simulated_time * 1e-3) + to.startup_time
         if time_spent > to.time_limit: