Dynamic Buffering for GPU Compute Work Distribution
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Solution Overview
Problem
Distributed architectures for GPUs face challenges in efficiently distributing compute work to different shaders, leading to workload imbalances due to varying completion rates of compute kernels, which can result in suboptimal performance and increased power consumption.
Innovation Solution
The implementation of dynamic buffering strategies, where the graphics processor adjusts the buffering capabilities based on the complexity of compute kernels, allowing for increased buffering for faster kernels and reduced buffering for slower ones, thereby maintaining high launch rates and preventing workload imbalances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If buffering is increased to maintain high launch rates, then productivity is improved, but workload imbalance increases leading to worse performance efficiency
Solution Approach 1:
The patent implements dynamic buffering control where the buffer depth is adjusted in real-time based on the completion status of compute kernels. The system monitors whether shaders are still working on previously dispatched kernels and modifies the buffer depth accordingly - increasing it when shaders are busy to maintain high launch rates, and decreasing it when shaders are idle to prevent workload imbalance. This dynamic adjustment resolves the contradiction by making the buffering strategy adaptive rather than static.
Solution Approach 2:
The system employs feedback mechanisms by monitoring the completion status of compute kernels dispatched to shaders. The completion status information is fed back to the buffer depth control logic, which then adjusts the buffer depth for subsequent kernel dispatches. This feedback loop enables the system to respond to actual shader workload status, maintaining optimal launch rates while preventing workload imbalance by adjusting buffering based on real-time system state.
2Reliability
If buffering is decreased to prevent workload imbalance, then workload balance is improved, but launch rates decrease leading to worse productivity
Solution Approach 1:
The buffer depth is dynamically adjusted based on shader workload status rather than being fixed. When the system detects that shaders have completed their current kernels (indicating they are ready for more work), it increases the buffer depth to enable higher launch rates. When shaders are still processing work, the buffer depth is reduced to prevent overload and workload imbalance. This dynamic behavior resolves the contradiction by adapting buffer size to actual system needs.
Solution Approach 2:
The patent changes the buffer depth parameter dynamically based on the completion status of compute kernels. Instead of using a fixed buffer depth, the system modifies this parameter in response to shader workload conditions. When completion status indicates shaders are ready, the buffer depth parameter is increased to improve launch rate; when shaders are busy, the parameter is decreased to maintain workload balance, thus resolving the contradiction through parameter adaptation.
3Productivity
If compute work is distributed to multiple shaders, then productivity is improved, but workload imbalance increases due to varying completion rates
Solution Approach 1:
The patent applies different buffering strategies to different shaders based on their individual workload completion status. Instead of using a uniform buffer depth for all shaders, the system tailors the buffer depth to each shader's current state - adjusting locally for each shader based on whether it has completed its current kernel or is still processing. This local quality approach enables parallel execution across multiple shaders while maintaining workload balance by customizing the dispatch strategy for each shader.
Solution Approach 2:
The system dynamically adjusts the buffer depth for each shader based on real-time completion status information. As shaders complete their work at different rates, the buffer depth control logic modifies the dispatch parameters for subsequent kernels on a per-shader basis. This dynamic adaptation allows the system to maintain high compute throughput through parallel execution while preventing workload imbalance by responding to individual shader performance characteristics.
Data Source
AI summary
Techniques are disclosed relating to dynamically adjusting buffering for distributing compute work in a graphics processor. In some embodiments, the graphics processor includes shader circuitry configured to process compute work from a compute kernel, multiple distributed workload parser circuits configured to send compute work to the shader circuitry, primary workload parser circuitry configured to send, via a communications fabric, compute work from the compute kernel to the distributed workload parser circuits, and buffer circuitry configured to buffer compute work received by one or more of the distributed workload parser circuits from the primary workload parser circuitry. In some embodiments, the graphics processor is configured to dynamically adjust a limit on the number of entries used in the buffer circuitry based on information indicating complexity of the compute kernel. This may advantageously maintain launch rates while reducing or avoiding workload imbalances, in some embodiments.