diff --git a/tensorflow/core/grappler/costs/op_level_cost_estimator.cc b/tensorflow/core/grappler/costs/op_level_cost_estimator.cc
index 0b28dc3b18c..477c9faddec 100644
--- a/tensorflow/core/grappler/costs/op_level_cost_estimator.cc
+++ b/tensorflow/core/grappler/costs/op_level_cost_estimator.cc
@@ -714,6 +714,8 @@ Status OpLevelCostEstimator::PredictNodeCosts(const OpContext& op_context,
   return PredictCostOfAnUnknownOp(op_context, node_costs);
 }
 
+// This method assumes a typical system composed of CPUs and GPUs, connected
+// through PCIe. To define device info more precisely, override this method.
 DeviceInfo OpLevelCostEstimator::GetDeviceInfo(
     const DeviceProperties& device) const {
   double gflops = -1;
@@ -755,13 +757,15 @@ DeviceInfo OpLevelCostEstimator::GetDeviceInfo(
     } else {
       gb_per_sec = 100;
     }
+  } else {
+    LOG_EVERY_N(WARNING, 1000) << "Unknown device type: " << device.type()
+                               << ", assuming PCIe between CPU and GPU.";
+    gflops = 1;  // Dummy value; data transfer ops would not have compute ops.
+    gb_per_sec = 12;  // default PCIe x16 gen3.
   }
   VLOG(1) << "Device: " << device.type() << " gflops: " << gflops
           << " gb_per_sec: " << gb_per_sec;
 
-  DCHECK_LT(0, gflops) << device.DebugString();
-  DCHECK_LT(0, gb_per_sec) << device.DebugString();
-
   return DeviceInfo(gflops, gb_per_sec);
 }