diff --git a/cpp/unittest/knowhere/knowhere_test.cpp b/cpp/unittest/knowhere/knowhere_test.cpp
index 1fd23250dea70c94633f2ef7f0af1b208ef8f648..0b9e6717e11b164ff7ea8704feeed18e4e11ccaa 100644
--- a/cpp/unittest/knowhere/knowhere_test.cpp
+++ b/cpp/unittest/knowhere/knowhere_test.cpp
@@ -21,11 +21,16 @@ using ::testing::TestWithParam;
 using ::testing::Values;
 using ::testing::Combine;
 
+constexpr int64_t DIM = 512;
+constexpr int64_t NB = 1000000;
 
 class KnowhereWrapperTest
     : public TestWithParam<::std::tuple<IndexType, std::string, int, int, int, int, Config, Config>> {
  protected:
     void SetUp() override {
+        zilliz::knowhere::FaissGpuResourceMgr::GetInstance().InitDevice(0);
+        zilliz::knowhere::FaissGpuResourceMgr::GetInstance().InitDevice(1);
+
         std::string generator_type;
         std::tie(index_type, generator_type, dim, nb, nq, k, train_cfg, search_cfg) = GetParam();
 
@@ -67,8 +72,8 @@ class KnowhereWrapperTest
     Config train_cfg;
     Config search_cfg;
 
-    int dim = 512;
-    int nb = 1000000;
+    int dim = DIM;
+    int nb = NB;
     int nq = 10;
     int k = 10;
     std::vector<float> xb;
@@ -106,9 +111,9 @@ INSTANTIATE_TEST_CASE_P(WrapperParam, KnowhereWrapperTest,
 //                                            Config::object{{"dim", 64}, {"k", 10}}
 //                            ),
                             std::make_tuple(IndexType::FAISS_IVFSQ8_MIX, "Default",
-                                            512, 1000000, 10, 10,
-                                            Config::object{{"dim", 512}, {"nlist", 1000}, {"nbits", 8}, {"metric_type", "L2"}},
-                                            Config::object{{"dim", 512}, {"k", 10}, {"nprobe", 5}}
+                                            DIM, NB, 10, 10,
+                                            Config::object{{"dim", DIM}, {"nlist", 1000}, {"nbits", 8}, {"metric_type", "L2"}},
+                                            Config::object{{"dim", DIM}, {"k", 10}, {"nprobe", 5}}
                             )
 //                            std::make_tuple(IndexType::NSG_MIX, "Default",
 //                                            128, 250000, 10, 10,
@@ -139,9 +144,6 @@ TEST_P(KnowhereWrapperTest, base_test) {
 TEST_P(KnowhereWrapperTest, to_gpu_test) {
     EXPECT_EQ(index_->GetType(), index_type);
 
-    zilliz::knowhere::FaissGpuResourceMgr::GetInstance().InitDevice(0);
-    zilliz::knowhere::FaissGpuResourceMgr::GetInstance().InitDevice(1);
-
     auto elems = nq * k;
     std::vector<int64_t> res_ids(elems);
     std::vector<float> res_dis(elems);