Exploring New Features
In an effort to delve deeper into the upcoming features of Windows 11 24H2, I sifted through various support documents. Among the notable updates is the introduction of WDDM 3.2, but a particularly intriguing feature is “User-mode work submission.” This capability, as described by Microsoft, aims to accelerate application performance.
According to a support document first highlighted by Windows Latest, Windows 11 24H2 enables applications to communicate more efficiently with the GPU. This enhancement allows apps to swiftly dispatch small tasks to the GPU, resulting in reduced latency and improved overall performance. For instance, graphics-intensive applications, such as video editing software, frequently send small workloads to the GPU. With user-mode work submission, this process is streamlined, as applications can directly submit their requests to utilize the GPU.
Microsoft elaborates, stating, “The goal is to improve performance of applications that submit small workloads frequently to the GPU.” Furthermore, the company notes that user-mode submission is expected to yield significant benefits for applications operating within containers or virtual machines (VMs).
Understanding GPU Doorbells
Windows 11 24H2 incorporates a mechanism known as “GPU doorbells,” which alerts the GPU when new tasks are queued. There are two distinct models of doorbells:
- Global Doorbells: A single notification system shared by all tasks, which the GPU continuously monitors.
- Dedicated Doorbells: Each task queue possesses its own notification system, simplifying the GPU's task processing.
However, as more applications begin to leverage the GPU for minor tasks, concerns arise regarding potential increases in power consumption. Fortunately, there is a solution. The user-mode work submission feature is designed to work in tandem with Windows’s engine state transition capabilities.
Power Management and Efficiency
For those unfamiliar, Windows 11’s display driver utilizes engine state transitions to regulate GPU power consumption. Typically, when a GPU operates in a high-power mode, it consumes more energy, which occurs only when the GPU is actively processing application or game requests. Conversely, when the GPU is idle, it enters a low-power mode to conserve energy.
The GPU can seamlessly transition between these performance modes based on tasks submitted through user-mode submission. When an application sends a request via this method, the engine state transition system recognizes the need for GPU resources and shifts the GPU into high-power mode. Once the tasks are completed and no further requests are pending, the system reverts the GPU back to low-power mode.
While the engine state transition system is not a new concept, the introduction of user-mode submission represents a significant advancement, allowing applications to efficiently access GPU resources. This innovation enables the GPU to respond to new tasks with minimal latency while simultaneously managing power consumption effectively.
Microsoft has already rolled out user-mode work submissions on Copilot+ PCs equipped with Snapdragon’s integrated GPU. The broader Windows user base, utilizing Intel, AMD, and Nvidia hardware, can anticipate the arrival of this feature with the Windows 11 24H2 update in the coming months.
