GPU Shared Register Allocation Cache for Reusing Secondary Programs
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Solution Overview
Problem
The finite pool of shared registers in a GPU limits performance due to redundant execution of secondary programs and inefficient allocation strategies, particularly in tile-based architectures and ray tracing scenarios.
Innovation Solution
A shared register allocation cache is used to manage register allocations, reducing redundant execution by reusing allocated shared registers and implementing eviction policies based on task termination and availability, allowing efficient allocation and reuse across different tasks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If more shared registers are added to increase available resources, then the GPU size increases, but the finite pool of registers still limits performance
Solution Approach 1:
A shared register allocation cache is introduced as an intermediary data structure between the finite pool of shared registers and the multiple tasks. The cache stores allocation metadata (cache index, allocation base, allocation size) to track which registers are allocated to which tasks, enabling efficient management of the limited register pool without increasing GPU size.
Solution Approach 2:
The system implements feedback mechanisms through the allocation cache that tracks register usage patterns. When a task needs registers, the system checks the cache for available allocations, and when tasks complete, the system updates the cache to reflect freed registers. This continuous feedback loop optimizes register distribution without requiring additional physical registers.
2Productivity
If shared registers are allocated to multiple tasks, then resource utilization improves, but deadlocks may occur when tasks wait for register allocation
Solution Approach 1:
The allocation cache performs preliminary actions by pre-tracking which registers are allocated to which tasks before actual register allocation occurs. When a task requests registers, the system checks the cache to determine availability and makes allocation decisions in advance, preventing situations where tasks would block each other waiting for registers.
Solution Approach 2:
The cache maintains continuous feedback about register allocation state, allowing the system to make informed decisions about which tasks can proceed and which must wait. This feedback mechanism enables the system to prevent deadlocks by identifying allocation conflicts before they occur and managing task scheduling accordingly.
3Adaptability or versatility
If secondary programs are executed multiple times for different tasks, then task flexibility is maintained, but redundant execution reduces performance
Solution Approach 1:
The allocation cache acts as an intermediary that stores information about which shared registers are allocated to which tasks and their corresponding secondary programs. This allows the system to determine whether a task can reuse registers from a previous allocation, avoiding redundant execution of secondary programs while maintaining the ability to execute them when necessary for task flexibility.
Solution Approach 2:
The cache creates a virtual copy of the allocation state, storing metadata about register allocations without actually duplicating the register contents. This allows the system to efficiently determine register availability and reuse patterns without re-executing secondary programs, thereby maintaining task flexibility while improving performance through avoidance of redundant operations.
Data Source
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AI summary
A method of managing shared register allocations in a GPU is described. The method comprises, in response to receiving an allocating task, searching a shared register allocation cache for a cache entry with a cache index that identifies a secondary program that is associated with the allocating task. In response to identifying a cache entry with a cache index that identifies the secondary program that is associated with the allocating task, the method returns an identifier of the cache entry and status information indicating a cache hit. Returning the identifier of the cache entry causes the identifier of the cache entry to be associated with the allocating task and returning the status information indicating a cache hit causes the allocating task not to be issued. To be accompanied, when published, by Figure 1 of the accompanying drawings.