memory query feature for cuda and metal (metal can only query total memory)

Author: swfly

src/backends/cuda/cuda_device.cpp

@@ -1186,6 +1186,22 @@ string CUDADevice::query(luisa::string_view property) noexcept {
     if (property == "device_name") {
         return "cuda";
     }
+    if (property == "total_memory") {
+        string memory = "0";
+        with_handle([&memory]{
+            size_t free_mem, total_mem;
+            cuMemGetInfo(&free_mem, &total_mem);
+            memory = to_string(total_mem);
+        });
+        return memory;
+    }
+    if (property == "free_memory") {
+        string memory = "0";
+        with_handle([&memory]{
+            size_t free_mem, total_mem;
+            cuMemGetInfo(&free_mem, &total_mem);
+            memory = to_string(free_mem);
+        });
     LUISA_WARNING_WITH_LOCATION("Unknown device property '{}'.", property);
     return {};
 }

src/backends/metal/metal_device.cpp

@@ -670,6 +670,17 @@ void MetalDevice::destroy_accel(uint64_t handle) noexcept {
 }
 
 string MetalDevice::query(luisa::string_view property) noexcept {
+
+    if (property == "total_memory") {
+        string memory = "0";
+        memory = std::to_string(_handle->recommendedMaxWorkingSetSize());
+        return memory;
+    }
+    if (property == "free_memory") {
+        string memory = "0";
+        memory = std::to_string(_handle->recommendedMaxWorkingSetSize());
+        return memory;
+    }
     LUISA_WARNING_WITH_LOCATION("Device property \"{}\" is not supported on Metal.", property);
     return {};
 }