diff --git a/analysis/optimizer/gridsearch_tuning_manager.py b/analysis/optimizer/gridsearch_tuning_manager.py
index 6a414d7884de0da22dc696b082b1fbd49469d00b..7391506525bdddf3f8afa91c41b1f99218c46272 100755
--- a/analysis/optimizer/gridsearch_tuning_manager.py
+++ b/analysis/optimizer/gridsearch_tuning_manager.py
@@ -83,11 +83,11 @@ class GridSearchTuningManager(object):
                 ret_para.append(copy.deepcopy(config))
         return ret_para
         
-    def do_gridsearch(self):
+    def do_gridsearch(self, num_done):
         """do the gridsearch on the spaces"""
         spaces = self.expand_parameters(self._dict_para)
         self._child_conn.send(len(spaces))
-        for space in spaces:
+        for space in spaces[num_done:]:
             LOGGER.info('space %s', space)
             iter_result = {}
             params = {}
diff --git a/analysis/optimizer/optimizer.py b/analysis/optimizer/optimizer.py
index 4cc3cd89f9b1a16cb494563d642a382fe3fadde8..231c6f757b4783e5c64d572b8ae081e6a7b1f128 100644
--- a/analysis/optimizer/optimizer.py
+++ b/analysis/optimizer/optimizer.py
@@ -317,8 +317,11 @@ class Optimizer(multiprocessing.Process):
                 # convert string option into index
                 options = abtuning_manager.get_options_index(options)
             elif self.engine == 'gridsearch':
+                num_done = 0
+                if self.y_ref is not None:
+                    num_done = len(self.y_ref)
                 gstuning_manager = GridSearchTuningManager(self.knobs, self.child_conn)
-                options, performance = gstuning_manager.do_gridsearch()
+                options, performance = gstuning_manager.do_gridsearch(num_done)
                 params, labels = gstuning_manager.get_best_params()
                 # convert string option into index
                 options = gstuning_manager.get_options_index(options)
diff --git a/common/tuning/optimizer.go b/common/tuning/optimizer.go
index a5ba64ecb3d04e598b6d08e656a2fc5d55bbf288..70824123ad4196b8947c1f7392c6b7e87748f812 100644
--- a/common/tuning/optimizer.go
+++ b/common/tuning/optimizer.go
@@ -139,7 +139,7 @@ func (o *Optimizer) createOptimizerTask(ch chan *PB.TuningMessage, iters int32,
 			return err
 		}
 	}
-	if o.Restart && iters <= int32(len(optimizerBody.Xref)) {
+	if o.Restart && iters <= int32(len(optimizerBody.Xref)) && (engine != "gridsearch") && (engine != "abtest") {
 		return fmt.Errorf("create task failed for client ask iters less than tuning history")
 	}
 	optimizerBody.MaxEval = iters