dnn(test): avoid calling of cv::setNumThreads() in tests directly

It is not necessary by default.
Also it breaks test system command-line parameters: --perf_threads / --test_threads

modules/dnn/perf/opencl/perf_convolution.cpp

@@ -77,8 +77,6 @@ OCL_PERF_TEST_P( ConvolutionPerfTest, perf, Combine(
     std::vector<Mat*> inpBlobs(1, &inpBlob);
     std::vector<Mat> outBlobs, internalBlobs;
 
-    cv::setNumThreads(cv::getNumberOfCPUs());
-
     Ptr<Layer> layer = cv::dnn::LayerFactory::createLayerInstance("Convolution", lp);
     std::vector<MatShape> inputShapes(1, shape(inpBlob)), outShapes, internals;
     layer->getMemoryShapes(inputShapes, 0, outShapes, internals);
@@ -99,7 +97,7 @@ OCL_PERF_TEST_P( ConvolutionPerfTest, perf, Combine(
     Mat inpBlob2D = inpBlob.reshape(1, outCn);
     Mat wgtBlob2D = wgtBlob.reshape(1, outCn*(inpCn/groups));
     Mat outBlob2D = outBlobs[0].reshape(1, outBlobs[0].size[0]);
-    declare.in(inpBlob2D, wgtBlob2D, WARMUP_RNG).out(outBlob2D).tbb_threads(cv::getNumThreads());
+    declare.in(inpBlob2D, wgtBlob2D, WARMUP_RNG).out(outBlob2D);
 
     // warmup
     layer->forward(inpBlobs, outBlobs, internalBlobs);

modules/dnn/perf/perf_convolution.cpp

@@ -60,8 +60,6 @@ PERF_TEST_P( ConvolutionPerfTest, perf, Combine(
     std::vector<Mat*> inpBlobs(1, &inpBlob);
     std::vector<Mat> outBlobs, internalBlobs;
 
-    cv::setNumThreads(cv::getNumberOfCPUs());
-
     Ptr<Layer> layer = cv::dnn::LayerFactory::createLayerInstance("Convolution", lp);
     std::vector<MatShape> inputShapes(1, shape(inpBlob)), outShapes, internals;
     layer->getMemoryShapes(inputShapes, 0, outShapes, internals);
@@ -81,7 +79,7 @@ PERF_TEST_P( ConvolutionPerfTest, perf, Combine(
     Mat inpBlob2D = inpBlob.reshape(1, outCn);
     Mat wgtBlob2D = wgtBlob.reshape(1, outCn*(inpCn/groups));
     Mat outBlob2D = outBlobs[0].reshape(1, outBlobs[0].size[0]);
-    declare.in(inpBlob2D, wgtBlob2D, WARMUP_RNG).out(outBlob2D).tbb_threads(cv::getNumThreads());
+    declare.in(inpBlob2D, wgtBlob2D, WARMUP_RNG).out(outBlob2D);
 
     layer->forward(inpBlobs, outBlobs, internalBlobs); /// warmup
 

modules/dnn/test/test_layers.cpp

@@ -107,8 +107,6 @@ void testLayerUsingCaffeModels(String basename, int targetId = DNN_TARGET_CPU,
     String inpfile = (useCommonInputBlob) ? _tf("blob.npy") : _tf(basename + ".input.npy");
     String outfile = _tf(basename + ".npy");
 
-    cv::setNumThreads(cv::getNumberOfCPUs());
-
     Net net = readNetFromCaffe(prototxt, (useCaffeModel) ? caffemodel : String());
     ASSERT_FALSE(net.empty());
 
@@ -536,8 +534,6 @@ void testLayerUsingDarknetModels(String basename, bool useDarknetModel = false,
     String inpfile = (useCommonInputBlob) ? _tf("blob.npy") : _tf(basename + ".input.npy");
     String outfile = _tf(basename + ".npy");
 
-    cv::setNumThreads(cv::getNumberOfCPUs());
-
     Net net = readNetFromDarknet(cfg, (useDarknetModel) ? weights : String());
     ASSERT_FALSE(net.empty());