Transaction Reordering via Index-Controlled Queue
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Solution Overview
Problem
Existing integrated circuits face performance limitations and hardware complexity due to the need for complex protocols that require responses to be delivered in the same order as requests, which can lead to frequency limitations and increased silicon usage, especially when using associative approaches like content addressable memory.
Innovation Solution
A transaction reordering arrangement that includes a queue and a controller to manage the order of responses, using index information to ensure responses are written and read in the same order as requests, allowing for out-of-order processing without the need for filtering or complex hardware, utilizing a virtual index mechanism to maintain order without associative approaches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If associative approaches using content addressable memory are used to maintain response order, then response ordering is achieved, but device complexity and silicon area increase significantly
Solution Approach 1:
The system segments the response ordering function into two independent parts: (1) a simple FIFO queue structure that stores responses, and (2) a controller that uses index information to control write positions. This segmentation replaces the monolithic content addressable memory with modular, simpler components that achieve the same ordering function with reduced complexity.
Solution Approach 2:
Index information acts as an intermediary mechanism between the request issuance and response receipt. The controller adds index information to requests, and uses this index information to control where responses are written in the queue, thereby mediating the ordering relationship without requiring complex associative memory structures.
2Reliability
If content addressable memory is used for response reordering, then response order is maintained, but processing frequency is limited
Solution Approach 1:
Instead of using content addressable memory to search for and retrieve responses based on request content (which limits frequency), the system inverts the approach by using a simple FIFO queue with index-based write control. This inversion replaces complex content-based addressing with simple positional writing, enabling higher processing frequencies while maintaining ordering.
Solution Approach 2:
The system uses simple, disposable index information structures rather than expensive, complex content addressable memory. The index information is added to requests, used to control queue writes, and then removed from responses - a lightweight, high-speed mechanism that enables frequent processing without the frequency limitations of CAM-based approaches.
3Reliability
If protocol-specific filtering is implemented to maintain response order, then ordering is achieved, but device complexity increases
Solution Approach 1:
The FIFO queue with index-based write control serves as a universal response ordering mechanism that works across different protocols without requiring protocol-specific filtering logic. The same simple structure handles ordering for various request types and protocols, eliminating the need for multiple specialized filtering components.
Solution Approach 2:
Index information serves as a protocol-agnostic intermediary that carries ordering information through the system. Rather than implementing protocol-specific filtering, the system uses this universal index mechanism to control response write positions, providing protocol-independent ordering with reduced complexity.
Data Source
AI summary
An embodiment of a transaction reordering arrangement is provided. The transaction reordering arrangement includes a queue into which respective responses to requests are writable and a controller configured to control a position in said queue to which said respective responses to said requests are written. The position is controlled such that the responses are read out of said queue in an order which corresponds to an order in which the requests are issued.