GPU Frequency Control for VR Frame Deadline Compliance
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Solution Overview
Problem
In virtual reality (VR), augmented reality (AR), and mixed reality (MR) applications, missing frame rendering deadlines can result in an unacceptable user experience, including motion-to-display latency, low frame-rates, and missing frames, which can cause dizziness or other unpleasant sensations.
Innovation Solution
A graphics processing unit (GPU) with a frequency management unit that dynamically adjusts its operating frequency on a per-frame basis, based on estimated processing time and remaining time before a deadline, to ensure timely frame rendering by increasing frequency if necessary and reducing it when workload is low, thereby maintaining a quality user experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the GPU operates at a high processing frequency to ensure timely frame rendering, then the frame rendering deadline is met, but the power consumption increases
Solution Approach 1:
The GPU operates frequency dynamically rather than statically. The frequency management unit continuously monitors rendering progress and adjusts the operating frequency in real-time based on the current workload and time remaining before the deadline, allowing the system to use high frequency only when necessary to meet deadlines while saving power during less critical periods
Solution Approach 2:
The operating frequency parameter is changed adaptively based on rendering progress. The system estimates the time required to complete the current frame and compares it with the remaining time before the deadline, then adjusts the frequency parameter accordingly - increasing it when the workload is heavy and decreasing it when the workload is light or the deadline is comfortably met
2Use of energy by moving object
If the GPU operates at a low processing frequency to save power, then the power consumption decreases, but the frame rendering deadline may be missed
Solution Approach 1:
The system implements a feedback mechanism where the frequency management unit continuously monitors the rendering progress and estimates the time remaining to complete the current frame. This feedback information is used to adjust the operating frequency in real-time, ensuring that the frequency is increased before the deadline if the rendering is behind schedule and decreased if the rendering is ahead of schedule
Solution Approach 2:
The frequency management unit performs preliminary estimation of the rendering time before the deadline expires. By estimating the time required to complete the current frame in advance and comparing it with the remaining time, the system can proactively adjust the frequency to ensure deadline compliance rather than reacting after the deadline is missed
3Use of energy by moving object
If the GPU frequency is adjusted dynamically on a per-frame basis, then the power consumption is optimized, but the system complexity increases
Solution Approach 1:
The frequency management unit is integrated within the GPU itself, allowing the GPU to autonomously monitor its own rendering progress and adjust its own operating frequency without requiring external control. This self-service approach reduces the complexity of external control systems while maintaining the benefits of dynamic frequency adjustment
Data Source
AI summary
A recommend operating frequency for a GPU is determine by an operating system. Timing information is used to estimate a time to complete the rendering of the current frame. If the estimate of the time to complete the rendering of the current frame is greater than the time left before the deadline, the operating frequency of the GPU is rapidly increased mid-frame. The new operating frequency is selected so that the rendering of the current frame can be expected to complete before the deadline arrives. Thus, when the rendering workload is low for a frame, the GPU is operated at a lower frequency thereby saving power. When the workload is high for a frame (even if the workload was lower for the previous frame), the GPU is operated at a higher frequency thereby ensuring a quality user experience.