Vector Processing Data Hazard Relaxation
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Solution Overview
Problem
Vector processing introduces significant data hazards, which are costly to handle and can lead to data inconsistency, especially when performing parallel operations on vectors, as existing solutions require stringent timing constraints to ensure data coherency, leading to increased hardware, latency, and power consumption.
Innovation Solution
A data processing apparatus with a pipelined processor that detects data dependencies and relaxes timing constraints for vector operations by determining data hazards between individual data elements within vectors, allowing operations to overlap or be performed in a different order without compromising data consistency, using a state machine to track the state of data elements and annotations to indicate potential dependencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If partitioned vector operations are performed in parallel to improve performance, then processing speed is improved, but data hazards and consistency costs increase
Solution Approach 1:
The patent segments the vector into multiple partitions and processes them in parallel using separate pipeline stages. Each partition can be processed independently by different functional units simultaneously, enabling parallel execution while maintaining data consistency through controlled data flow between stages.
Solution Approach 2:
The patent performs preliminary actions by detecting data dependencies between vector operations before execution and determining the necessary timing constraints. This advance analysis allows the system to establish safe execution windows and data hazard prevention mechanisms before the actual parallel processing begins, ensuring consistency without sacrificing performance.
2Reliability
If timing constraints are enforced to ensure data coherency, then data consistency is maintained, but hardware complexity and power consumption increase
Solution Approach 1:
The patent applies timing constraints and consistency checks locally only where data dependencies actually exist between vector operations. Rather than enforcing global synchronization across all operations, the system identifies specific data hazard points and applies constraints only at those locations, reducing overall hardware complexity while maintaining necessary data coherency.
3Reliability
If timing constraints are enforced to ensure data coherency, then data consistency is maintained, but processing latency increases
Solution Approach 1:
The patent performs preliminary detection of data dependencies and determination of timing constraints before vector execution. This advance analysis allows the system to establish safe execution windows and overlap independent operations, minimizing the impact of necessary consistency checks on overall processing latency.
Solution Approach 2:
The patent dynamically adjusts timing constraints based on the specific data dependencies detected for each vector operation sequence. Rather than using fixed, conservative timing margins, the system determines precise constraint windows that are tight enough to maintain consistency but loose enough to allow maximum parallelism and minimize latency.
Data Source
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AI summary
A data processing apparatus for processing a stream of vector instructions for performing operations on vectors, said vectors each comprising a plurality of data elements is disclosed. The data processing apparatus comprises: a register bank having a plurality of registers for storing the vectors being processed; a pipelined processor for processing the stream of vector instructions; the pipelined processor comprising circuitry configured to detect data dependencies for the vectors processed by the stream of vector instructions and stored in the plurality of registers and to determine constraints on timing of execution for the vector instructions such that no register data hazards arise, said register data hazards arising where two accesses to a same register, at least one of said accesses being a write, occur in an order different to an order of said instruction stream such that an access occurring later in said instruction stream starts before an access occurring earlier in said instruction stream has completed. The pipelined processor comprises data element hazard determination circuitry configured to determine for at least some of the data elements within vectors where data dependencies have been identified, whether the data dependencies identified for the vectors exist for each of the at least some of the data elements, and if not to relax the determined constraints on timing of execution for an instruction processing the data element.