Content-Addressable Memory Block Segmentation for Power Reduction
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Solution Overview
Problem
Current packet switching technologies face inefficiencies in power consumption and heat generation during content-addressable memory lookup operations, particularly when performing longest prefix matching, as they search all memory entries simultaneously, leading to increased power usage and heat production.
Innovation Solution
The implementation of a content-addressable memory with multiple blocks, where only designated blocks are searched based on a profile identifier and search key, reducing power consumption and heat by partitioning entries and performing lookup operations in parallel, with fully expanded entries in one set and less fully expanded entries in another, allowing sequential or parallel searching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all content-addressable memory entries are searched simultaneously during lookup operations, then complete search coverage is achieved, but power consumption and heat generation increase
Solution Approach 1:
The content-addressable memory is divided into multiple blocks, and the search process is segmented to only activate and search relevant blocks based on the search key characteristics, rather than searching all blocks simultaneously. This segmentation reduces the number of active memory cells during each lookup operation, thereby reducing power consumption while maintaining complete search coverage through selective block activation.
2Reliability
If all content-addressable memory entries are searched simultaneously during lookup operations, then complete search coverage is achieved, but heat generation increases
Solution Approach 1:
By segmenting the memory into blocks and only activating relevant blocks for each search operation, the total number of simultaneously active memory cells is reduced. This decreases the aggregate heat generation from memory access operations while ensuring that the relevant block containing the match is still searched, maintaining search completeness.
3Use of energy by stationary object
If multiple lookup operations are processed sequentially, then power consumption is reduced, but processing speed decreases
Solution Approach 1:
The memory is segmented into multiple blocks that can be independently activated. Multiple lookup operations can be processed in parallel by distributing them across different blocks, while still maintaining lower power consumption compared to searching all blocks for every operation. This parallel block processing increases lookup speed without requiring full memory activation for each search.
Solution Approach 2:
The system dynamically selects which memory blocks to activate based on the characteristics of the search key and the content-addressable memory profile identifier. This dynamic block selection enables flexible parallel processing of multiple lookups by activating only the necessary blocks, achieving a balance between speed and power consumption.
4Measurement precision
If the entire content-addressable memory is searched for each lookup operation, then accurate longest prefix matching is achieved, but processing time increases
Solution Approach 1:
The memory is divided into blocks, and the search is confined to only those blocks that are relevant to the current lookup operation. This block-level segmentation maintains matching accuracy by ensuring that all relevant entries are searched within the activated blocks, while reducing search time by avoiding traversal of irrelevant blocks.
Solution Approach 2:
The system performs preliminary determination of which blocks to search based on the content-addressable memory profile identifier and search key before executing the full lookup operation. This preliminary block selection action reduces the effective search space, maintaining accuracy while decreasing the time required for each lookup operation.
Data Source
AI summary
In one embodiment, a content-addressable memory has multiple blocks of content-addressable memory entries, including different first and second sets of content-addressable memory blocks. One embodiment determines the first set of content-addressable memory blocks based on a content-addressable memory profile identifier and a search key and then performs a first content-addressable memory lookup operation in each of the first set of content-addressable memory blocks, but not in the second set of content-addressable memory blocks, based on the search key. If at least one entry is match, a corresponding result is identified. Otherwise, in one embodiment, the second set of content-addressable memory blocks is determined based on the content-addressable memory profile identifier but not based on the search key, and a search is made therein to identify a matching result or that no match was determined. In one embodiment, a matching result determines how a packet is processed.