--- title: Analyzing the memory usage of your Metal app framework: xcode role: article role_heading: Article path: xcode/analyzing-the-memory-usage-of-your-metal-app --- # Analyzing the memory usage of your Metal app Keep your app alive in the background by managing its memory footprint. ## Overview Overview Instruments provides the Game Memory template to help you understand the memory growth in your Metal app. Keeping a small memory footprint allows the system to keep the app alive in the background longer, especially on devices with more constrained memory capacity. For more information, see Profile and optimize your game’s memory. Open the Game Memory template Start the memory analysis from your Xcode project by choosing Product > Profile, or by pressing Command-I. Alternatively, you can launch Instruments and then select the process from the drop-down list. In the Template Selection window, select Game Memory. Get to know the instruments Record an Instruments capture Begin collecting the data by clicking the Record button. Within your app, perform the actions that reproduce the memory problem, and then click the Record button to stop recording. Analyze your app’s memory allocations The Game Memory template shows both memory allocations and memory footprint. Memory allocations occupy space in the virtual memory address space. When your app allocates memory, these new allocations may not immediately take up space on physical memory. It’s not until your app uses these allocations that they consume physical memory. The Allocations track provides a detailed view of memory allocations, their sizes, and object reference counts. note: The Allocations track doesn’t include Metal resources with private storage mode — only managed and shared storage modes. The Statistics view in the bottom detail area displays the categories of memory allocations. At the top of the Category column, there are three umbrella categories that summarize all allocations: Below them, you can find more detailed categories. Metal resource allocations are in the VM: IOAccelerator category, and drawables are in VM: IOSurface. To inspect the individual allocations in a category, click the arrow button next to the category name in the table. After selecting a category, you can sort the table by the Size column to find the largest memory allocation during the selected time range. You can also select an allocation in the list to view its description and stack trace in the inspector on the right. Analyze Metal resource allocations The Metal Resource Events track displays a history of all Metal-specific resource allocations and deallocations, along with their labels (see Naming resources and commands). The Resource Events view in the bottom detail area lists the resource allocation and deallocation events. It includes events from created or destroyed resources in the selected time range. Not all resources in the list persisted until the end of the time range. Analyze your app’s total virtual memory footprint The Allocations track and the Metal Resource Events track both highlight memory allocations. However, allocations don’t always translate to memory footprint. The VM Tracker track shows the noncompressed and compressed/swapped dirty memory that together make up your app’s memory footprint. Memory operates on the granularity of pages, and those pages can be either clean or dirty. To conserve the amount of physical memory that your app uses, the system may compress or swap out some dirty pages that your app hasn’t accessed recently. important: The system charges your app for any compressed/swapped memory based on its orginal size before compression. The center timeline area graphs the following metrics: The corresponding columns are also available in the Summary view of the bottom detail area. There, you can expand the VM region types. In the mapped file type in the screenshot below, you can see the memory-mapped file of the bistro scene that the Modern Renderer app loaded: ## See Also ### Graphics - [Analyzing the performance of your Metal app](xcode/analyzing-the-performance-of-your-metal-app.md)