Mixed-Precision Floating-Point Pipeline Scheduling for GPU Throughput
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Solution Overview
Problem
Existing processor architectures face challenges in efficiently executing operations of different precisions while balancing performance and power consumption, particularly in graphics processing units (GPUs), as they often rely on traditional methods that lead to inefficiencies in power usage and throughput.
Innovation Solution
Implementing superscalar techniques that dispatch multiple instructions to execution units with different capabilities, including 32-bit and 16-bit pipelines, and utilizing higher-precision pipelines to execute lower-precision operations with two rounding steps to maintain precision and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If higher-precision datapath circuitry is used to execute operations, then manufacturing precision and computational accuracy are improved, but power consumption increases
Solution Approach 1:
The processor is divided into separate execution pipelines, each dedicated to specific precision levels (e.g., 16-bit pipeline, 32-bit pipeline). This segmentation allows the system to select the appropriate precision level for each operation independently, avoiding the need to always use high-precision circuitry and thus reducing overall power consumption while maintaining computational accuracy when needed.
Solution Approach 2:
The system dynamically selects which pipeline to execute operations based on the precision requirements of the instructions. The scheduler dynamically dispatches instructions to appropriate pipelines, enabling the processor to adapt its precision level in real-time based on workload demands, thereby optimizing the trade-off between accuracy and power consumption.
2Adaptability or versatility
If multiple pipelines with different precisions are implemented, then adaptability to different operations is improved, but device complexity increases
Solution Approach 1:
Each execution pipeline is designed to be universal within its precision class, capable of executing various operations (addition, multiplication, FMA) at that precision level. The pipelines share common functional units and control logic, reducing the overall complexity compared to having separate dedicated circuits for each operation type while maintaining high adaptability to different computational needs.
Solution Approach 2:
The system manages complexity by parameterizing the pipeline architecture around precision levels rather than creating entirely separate systems. The pipelines differ primarily in their data width parameters (16-bit vs. 32-bit), allowing the same architectural framework to serve multiple precision requirements with minimal additional complexity.
3Use of energy by moving object
If lower-precision operations are executed using lower-precision circuitry, then power consumption is reduced, but throughput may be limited
Solution Approach 1:
By segmenting the execution into separate precision-based pipelines, the system can execute lower-precision operations on dedicated 16-bit pipelines that are optimized for power efficiency, while simultaneously executing higher-precision operations on 32-bit pipelines. This parallel segmentation enables the system to maintain high throughput across all precision levels without compromising power consumption for specific operation types.
Solution Approach 2:
The scheduler ensures continuous utilization of all available pipelines by dynamically dispatching operations to appropriate precision levels based on availability and requirements. This continuous dispatching minimizes idle time and maintains steady throughput while allowing the system to leverage lower-precision, lower-power circuits for suitable operations.
Data Source
AI summary
Techniques are disclosed relating to scheduling instructions for floating-point execution units with different capabilities. In some embodiments, a first pipeline is configured to execute a first type of floating-point operation on operands having up to a first precision and a second pipeline is configured to execute the first type of floating-point operation on operands having up to a second, greater precision. In some embodiments, round circuitry is configured to round results from an output precision of the second pipeline to an output precision of the first pipeline. Scheduling circuitry may select operations for issuance for a given cycle from multiple ready threads. This may include to prioritize a determined highest-precision operation of the first type from ready operations and assign the determined operation to a lowest-precision pipeline, of the multiple pipelines, that is configured to perform the first type of operation according to the operand precision of the determined operation.