Reconfigurable Buffer Speculative Vector Write Control
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Solution Overview
Problem
Existing data processing systems face challenges in speculative vectorization, particularly with vector store operations, as they cannot handle unpredictable loop iterations, leading to difficulties in updating cache/memory and maintaining data integrity.
Innovation Solution
A data processing apparatus with a reconfigurable buffer and speculation control circuitry that performs speculative data write operations, storing vector elements in a buffer until a commit condition is met, allowing dynamic adjustment of speculation width to manage overflow conditions and ensure accurate data storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If speculative vector store operations are performed with predetermined vector element count, then data processing performance is improved, but the system cannot handle loops with unpredictable iterations
Solution Approach 1:
The patent implements dynamic speculation width adjustment, where the number of vector elements processed speculatively is not fixed but can be adjusted based on runtime conditions. The speculation control circuitry modifies the speculation width when overflow conditions are detected, allowing the system to adapt to different loop iteration scenarios while maintaining speculative execution performance benefits
Solution Approach 2:
The system changes the parameter of speculation width dynamically. When an overflow condition is detected in the reconfigurable buffer, the speculation control circuitry reduces the speculation width parameter, thereby adjusting the number of vector elements to be processed. This parameter change enables the system to handle unpredictable loop iterations while maintaining efficient speculative vector store operations
2Reliability
If reconfigurable buffer size is increased to handle more vector elements, then overflow conditions are reduced, but device complexity increases
Solution Approach 1:
Instead of providing a large fixed-size buffer, the patent implements a reconfigurable buffer whose capacity can be dynamically adjusted. The buffer can be reconfigured to store different numbers of vector elements based on the current speculation width, allowing the system to optimize buffer usage for different execution scenarios without requiring a large fixed buffer capacity
Solution Approach 2:
The buffer capacity parameter is made changeable rather than fixed. When speculation width needs to be reduced due to overflow conditions, the reconfigurable buffer adjusts its capacity accordingly. This dynamic parameter adjustment allows the system to maintain reliability by preventing overflow while avoiding the complexity and resource overhead of a permanently large buffer
3Device complexity
If speculation width is reduced to prevent buffer overflow, then buffer capacity requirements are reduced, but the number of vector elements processed decreases
Solution Approach 1:
The speculation width is implemented as a dynamic parameter that can be adjusted at runtime rather than being fixed. The speculation control circuitry monitors buffer usage and dynamically reduces speculation width only when overflow conditions are detected, allowing the system to maintain high productivity during normal operation while adapting to prevent overflow when necessary
Solution Approach 2:
The system changes the speculation width parameter adaptively based on runtime conditions. Rather than using a conservative fixed width that limits productivity, the system starts with a larger speculation width to maximize vector element processing and only reduces it when overflow conditions are actually detected, thereby maintaining high productivity while preventing buffer overflow
Data Source
AI summary
A data processing apparatus and method for performing speculative vector access operations are provided. The data processing apparatus has a reconfigurable buffer accessible to vector data access circuitry and comprising a storage array for storing up to M vectors of N vectors elements. The vector data access circuitry performs speculative data write operations in order to cause vector elements from selected vector operands in a vector register bank to be stored into the reconfigurable buffer. On occurrence of a commit condition, the vector elements currently stored in the reconfigurable buffer are then written to a data store. Speculation control circuitry maintains a speculation width indication indicating the number of vector elements of each selected vector operand stored in the reconfigurable buffer. The speculation width indication is initialized to an initial value, but on detection of an overflow condition within the reconfigurable buffer the speculation width indication is modified to reduce the number of vector elements of each selected vector operand stored in the reconfigurable buffer. The reconfigurable buffer then responds to a change in the speculation width indication by reconfiguring the storage array to increase the number of vectors M and reduce the number of vector elements N per vector. This provides an efficient mechanism for supporting performance of speculative data write operations.