Proxy Identifier Hazard Checking Circuitry
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing data processing systems face challenges in efficiently performing hazard checking between data access transactions due to the large size of physical addresses, which requires large comparators, increasing power consumption and complicating circuit timing.
Innovation Solution
The use of proxy identifiers with fewer bits than physical addresses, combined with translation lookaside buffers (TLBs) and hazard checking circuitry, allows for efficient detection of hazards by comparing TLB entry identifiers instead of full physical addresses, reducing comparator size and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full physical addresses are used for hazard checking, then accurate hazard detection is achieved, but comparator size and power consumption increase
Solution Approach 1:
The physical address is segmented into a proxy identifier portion and a remaining portion. The hazard checking circuitry compares only the proxy identifier portions of addresses, which are smaller than full physical addresses. This segmentation maintains hazard detection accuracy for addresses within the same translation lookaside buffer (TLB) entry while reducing comparator size and power consumption.
Solution Approach 2:
A proxy identifier is introduced as an intermediary representation of the physical address. Instead of comparing full physical addresses directly, the system compares these simplified proxy identifiers. The proxy identifier acts as a mediator that preserves the essential comparison functionality while reducing the complexity and power consumption of the hazard checking operation.
2Measurement precision
If full physical addresses are used for hazard checking, then accurate hazard detection is achieved, but circuit complexity and area increase
Solution Approach 1:
The physical address comparison function is segmented into two parts: proxy identifier comparison and full address comparison. The hazard checking circuitry first compares the smaller proxy identifier portions, which reduces the complexity and area of the primary comparison logic. This segmentation allows the system to maintain accurate hazard detection while using simpler, smaller comparators for the most common case.
3Use of energy by moving object
If proxy identifiers with fewer bits are used, then comparator size and power consumption are reduced, but address translation timing may be affected
Solution Approach 1:
The proxy identifier is determined and prepared in advance as part of the address translation process, before the actual hazard checking occurs. By pre-computing and storing the proxy identifier alongside the physical address in the translation lookaside buffer (TLB), the system eliminates the need for time-consuming full address comparisons during hazard checking, thus reducing the time penalty while maintaining energy savings.
Data Source
AI summary
An apparatus comprises processing circuitry to process data access operations specifying a virtual address of data to be loaded from or stored to a data store, and proxy identifier determining circuitry to determine a proxy identifier for a data access operation to be processed by the data access circuitry, the proxy identifier having fewer bits than a physical address corresponding to the virtual address specified by the data access operation. The processing circuitry comprises at least one buffer to buffer information (including the proxy identifier) associated with one or more pending data access operations awaiting processing. Address translation circuitry determines the physical address corresponding to the virtual address specified for a data access operation after that data access operation has progressed beyond said at least one buffer.