Latency Buffered Scoreboard for Graphics Pipeline Coherence
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Solution Overview
Problem
Existing graphics systems face performance bottlenecks and increased latency due to the scoreboard mechanism's inefficiencies in managing concurrent rendering operations and accessing graphics memory, particularly in mitigating read-modify-write hazards.
Innovation Solution
Implementing a latency buffered scoreboarding process in the graphics pipeline, which accounts for the initiation and completion of parameter evaluation for each pixel through ID matching and buffering, using L1 and L2 caches to reduce memory access latency and ensure data coherence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional scoreboard mechanism is used to manage concurrent rendering operations, then read-modify-write hazards can be mitigated, but graphics memory access latency increases and performance decreases
Solution Approach 1:
The patent applies preliminary action by pre-fetching pixel data into the pixel data cache before it is actually needed for rendering operations. The scoreboard mechanism is enhanced to predictively load data into the cache, so that when concurrent rendering operations need to access pixel data, the data is already available in the cache, thereby reducing memory access latency while still maintaining proper hazard mitigation through the scoreboard's coordination of concurrent access.
2Productivity
If multiple primitives are processed concurrently to improve rendering throughput, then productivity increases, but managing R-M-W hazards becomes more complex and latency increases
Solution Approach 1:
The patent extracts the hazard mitigation function from the traditional scoreboard mechanism alone and separates it into two components: the scoreboard continues to track and coordinate concurrent primitive processing, while a dedicated pixel data cache handles the data storage and retrieval. This extraction allows the scoreboard to focus solely on coordination without the overhead of direct memory management, reducing its latency impact while maintaining concurrent processing capability.
Solution Approach 2:
The pixel data cache acts as an intermediary between the scoreboard mechanism and the graphics memory. Instead of the scoreboard directly managing memory access for each pixel operation, the cache mediates by buffering pixel data and providing it to rendering units. This intermediary layer reduces the latency burden on the scoreboard while enabling efficient concurrent access to pixel data through cache-based sharing.
3Productivity
If pixel data is frequently accessed from graphics memory during rendering, then rendering operations can be performed, but memory access latency reduces performance
Solution Approach 1:
The system performs preliminary action by pre-loading pixel data into the pixel data cache before it is needed for rendering operations. The enhanced scoreboard mechanism predicts which pixels will be accessed and initiates cache loading in advance, so that when rendering operations require pixel data, it is already available in the cache, eliminating the need for slow graphics memory access during critical rendering paths.
Solution Approach 2:
The patent introduces a new dimensional layer of data storage by adding the pixel data cache between the rendering units and graphics memory. This creates a hierarchical memory structure with the cache providing fast access for frequently used pixel data, while the graphics memory serves as slower bulk storage. This dimensional addition allows the system to achieve fast rendering performance for accessed pixels without sacrificing the capacity of the underlying graphics memory.
Data Source
AI summary
A method in system for latency buffered scoreboarding in a graphics pipeline of a graphics processor. The method includes receiving a graphics primitive for rasterization in a raster stage of a graphics processor and rasterizing the graphics primitive to generate a plurality pixels related to the graphics primitive. An ID stored to account for an initiation of parameter evaluation for each of the plurality of pixels as the pixels are transmitted to a subsequent stage of the graphics processor. A buffer is used to store the fragment data resulting from the parameter evaluation for each of the plurality of pixels by the subsequent stage. The ID and the fragment data from the buffering are compared to determine whether they correspond to one another. The completion of parameter evaluation for each of the plurality of pixels is accounted for when the ID and the fragment data match and as the fragment data is written to a memory.