Raster Order View Enforcement for GPU Wave Dependency
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Solution Overview
Problem
Graphics Processing Units (GPUs) face challenges in executing waves out of order due to hardware limitations, leading to potential errors in rendering images or video frames, particularly when multiple waves overlap and dependencies between threads are not properly managed.
Innovation Solution
Implementing a raster order view enforcement mechanism using pixel dependency data structures and thread dependency linked lists, where each wave generates a dependency chain and threads wait for older waves to complete before executing, ensuring that threads with dependencies are executed only after their dependent threads have finished and become inactive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple waves are launched in parallel on the GPU to generate pixel values, then processing speed and productivity are improved, but the waves may execute out of order due to hardware limitations, leading to rendering errors
Solution Approach 1:
The patent applies preliminary action by generating dependency chains for all waves before execution begins. The control logic pre-establishes the correct execution order by analyzing pixel dependencies between waves and creates a execution schedule that ensures waves execute in the proper raster order, preventing out-of-order execution errors while maintaining parallel processing capabilities
Solution Approach 2:
The patent introduces an intermediary control logic component that mediates between the parallel wave execution and the final pixel output. This control logic monitors wave completion status, tracks pixel dependencies, and coordinates the execution order of waves, acting as a mediator that ensures correct rendering order without requiring the GPU hardware itself to enforce sequence
2Productivity
If waves are executed out of order to maximize hardware utilization, then productivity is improved, but manufacturing precision and reliability of the rendering output deteriorate
Solution Approach 1:
The patent applies dynamics by creating a flexible execution model where waves can be launched in parallel but their actual execution timing is dynamically adjusted based on dependency chains. The system maintains hardware utilization by keeping multiple waves ready for execution while dynamically determining the precise moment each wave should execute to maintain correct raster order, balancing parallelism with precision
3Reliability
If dependency chains are generated for all waves to ensure correct execution order, then reliability and rendering accuracy are improved, but device complexity and processing overhead increase
Solution Approach 1:
The patent applies segmentation by dividing the dependency analysis into manageable components: pixel-level dependency tracking, wave-level dependency chains, and thread-level execution control. This segmentation allows the complex control logic to be broken down into modular functions that can be implemented efficiently, reducing the overall complexity burden while maintaining reliability
Data Source
AI summary
Systems, apparatuses, and methods for implementing raster order view enforcement techniques are disclosed. A processor includes a plurality of compute units coupled to one or more memories. A plurality of waves are launched in parallel for execution on the plurality of compute units, where each wave comprises a plurality of threads. A dependency chain is generated for each wave of the plurality of waves. The compute units wait for all older waves to complete dependency chain generation prior to executing any threads with dependencies. Responsive to all older waves completing dependency chain generation, a given thread with a dependency is executed only if all other threads upon which the given thread is dependent have become inactive. When executed, the plurality of waves generate a plurality of pixels to be driven to a display.