Register File Virtualization via Shadow Buffer Segmentation
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Solution Overview
Problem
Current register file designs in processors face limitations due to micro-architectural constraints such as size and latency issues in data transfers between the register file and the SRAM backing store, which hinder performance, especially in multithreaded environments and large working sets.
Innovation Solution
The implementation of register file virtualization through hardware extensions that enable parallel streaming of data between SRAM and shadow buffers, allowing for dynamic partitioning of register file entries into domains with selectable modes for latching and transport, effectively increasing the functional capacity of the register file.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the register file size is increased to accommodate larger working sets, then the functional capacity is improved, but the area and complexity of the register file increases
Solution Approach 1:
The register file is segmented into multiple domains (e.g., domain 0 and domain 1) that can be independently accessed. Each domain has its own read and write ports, allowing parallel operations. This segmentation enables the register file to function as if it has larger capacity by distributing data across domains, while each physical domain remains manageable in size and complexity.
Solution Approach 2:
Domain identification logic and multiplexing circuitry are introduced as intermediaries between the processor cores and the physical register file domains. These intermediaries translate virtual register file addresses into physical domain addresses, enabling the system to present a larger logical register file capacity without proportionally increasing the physical structure complexity.
2Productivity
If separate read and write ports are implemented to improve performance, then the access bandwidth is increased, but the device complexity increases
Solution Approach 1:
The register file is divided into multiple domains, each with dedicated read and write ports. This segmentation allows multiple simultaneous read and write operations to occur in parallel across different domains, significantly increasing the overall access bandwidth. The complexity is distributed across domains rather than concentrated in a single complex port structure.
Solution Approach 2:
The system dynamically selects which domain to access based on the domain identification logic. This dynamic domain selection enables flexible routing of read and write operations to appropriate domains, optimizing performance while managing complexity through adaptive control rather than static complex interconnections.
3Quantity of substance
If the register file capacity is increased to support multithreaded environments, then the working set capacity is improved, but the access latency increases
Solution Approach 1:
By segmenting the register file into multiple domains with independent ports, the system can service multiple threads simultaneously in different domains. This parallelism across domains reduces the effective access latency for multithreaded workloads, as threads can access data from different domains at the same time rather than sequentially.
Solution Approach 2:
The domain identification logic pre-determines which domain contains the required data based on the register file address. This preliminary identification allows the system to directly route to the correct domain without sequential searching or arbitration delays, reducing access latency while supporting large working sets across multiple domains.
Data Source
AI summary
Methods and apparatus relating to register file virtualization techniques are described. In an embodiment, a register file includes a plurality of register file cells. Each of the register file cells includes a register file entry and a shadow buffer. Logic circuitry causes storage of input data to the shadow buffer, while data stored in the register file entry is accessible to perform one or more operations. Other embodiments are also disclosed and claimed.