GPU GPR Release Mechanism for Shader Concurrency
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Solution Overview
Problem
In graphics processing, the allocation of General Purpose Registers (GPRs) to shader programs often results in an overabundance of registers being allocated at compile time to accommodate the most complex branches, even if simpler branches are executed, leading to reduced concurrency and performance due to fewer threads being simultaneously resident in the GPU.
Innovation Solution
A programmable GPR release mechanism is introduced that deallocates excess GPRs at runtime based on the determined value of constants, allowing more threads to be resident in the GPU by identifying unutilized branches and releasing unnecessary GPRs for subsequent threads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GPRs are allocated at compile time to accommodate the most complex branches, then the shader can execute any branch correctly, but the number of simultaneously resident threads decreases
Solution Approach 1:
The patent implements dynamic GPR allocation by introducing a GPR release mechanism that operates at runtime. The system determines the actual value of constants during shader execution, identifies which branches are actually taken, and releases GPRs that are not needed for the executed branch. This transforms the static GPR allocation into a dynamic system that adapts to actual runtime conditions, allowing the same shader to use fewer GPRs when complex branches are not executed, thereby increasing thread concurrency while maintaining execution correctness.
2Adaptability or versatility
If GPRs are allocated based on possible branches with undetermined constants, then all potential execution paths are supported, but excess GPRs are allocated reducing GPU performance
Solution Approach 1:
The patent applies the extraction principle by removing unnecessary GPR allocations from the shader execution. The GPR release mechanism extracts and releases the specific GPRs that correspond to unexecuted branches based on constant value determination. This allows the system to maintain support for multiple execution paths (adaptability) while removing the excess resource allocation that harms performance, achieving a balance between versatility and productivity.
Solution Approach 2:
The system changes the GPR allocation parameter dynamically based on runtime conditions. Instead of using a fixed GPR allocation determined at compile time, the system adjusts the effective GPR usage by releasing unused registers based on the actual constant values and executed branches. This parameter change approach allows the shader to adapt its resource usage to actual execution needs, improving GPU performance while maintaining branch execution capability.
3Adaptability or versatility
If the compiler allocates GPRs for the most complex branch, then the shader can handle any constant value, but fewer threads can be resident in the GPU
Solution Approach 1:
The patent transforms static GPR allocation into a dynamic system where the effective GPR usage changes based on runtime constant values. The GPR release mechanism dynamically determines which GPRs are actually needed based on the executed branch, allowing the system to maintain adaptability for handling any constant value while optimizing thread residency by releasing unused GPRs during actual execution.
Data Source
AI summary
This disclosure provides systems, devices, apparatus and methods, including computer programs encoded on storage media, for GPR optimization in a GPU based on a GPR release mechanism. More specifically, a GPU may determine at least one unutilized branch within an executable shader based on constants defined for the executable shader. Based on the at least one unutilized branch, the GPU may further determine a number of GPRs that can be deallocated from previously allocated GPRs. The GPU may deallocate, for a subsequent thread within a draw call, the number of GPRs from the previously allocated GPRs during execution of the executable shader based on the determined number of GPRs to be deallocated.