Cache Read Queue Prefetching for Memory Transfer Latency
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Solution Overview
Problem
The performance of caches is hindered by the need to frequently update data due to their small storage space and the long latency in data transfer from memory, leading to significant waiting times and reduced efficiency.
Innovation Solution
Implementing a cache system with multiple request queues and buffers to manage read and write requests, including pre-sending requests to the memory controller and handling read-after-write situations to reduce waiting times and optimize data retrieval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is transferred from memory to cache, then the cache can store and retrieve data, but the long physical distance causes hundreds of clock cycles delay
Solution Approach 1:
The patent implements a preliminary action by having the memory controller pre-fetch and store data in a buffer before the cache actually needs it. The cache controller predicts which data will be needed and triggers memory transfers in advance, so that when the cache requests the data, it is already available in the buffer, eliminating the hundreds of clock cycle delay.
Solution Approach 2:
The patent introduces a buffer as an intermediary component between the memory controller and the cache. This buffer acts as a mediator that holds data temporarily, allowing the cache to retrieve data from the buffer (short distance) instead of directly from memory (long distance), thus reducing the transfer time while maintaining data availability.
2Productivity
If the cache stores more data to reduce updates, then the storage capacity increases, but the cache size is physically limited
Solution Approach 1:
The patent extends the storage capacity in another dimension by adding a buffer associated with the memory controller, which is separate from the cache's physical storage space. This creates an extended storage hierarchy where the buffer provides additional capacity without increasing the cache's physical volume, allowing more data to be staged for retrieval without violating the cache's size constraints.
3Reliability
If the cache waits for memory to transfer data, then data consistency is maintained, but the cache spends most working time waiting
Solution Approach 1:
The cache controller performs preliminary actions by predicting which data will be needed and triggering memory transfers in advance. This allows the cache to prepare data before it is actually requested, maintaining data consistency while reducing the time the cache spends in a waiting state, thereby improving working efficiency.
Solution Approach 2:
The patent implements a feedback mechanism where the cache controller monitors cache access patterns and uses this information to predict future data needs. This feedback loop allows the system to dynamically adjust pre-fetching behavior, ensuring data consistency while optimizing the timing of memory transfers to minimize waiting time and maximize productivity.
Data Source
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AI summary
The present application provides a cache, a cache management method, and an electronic device, wherein the cache includes: a plurality of cache lines, a first read request queue and a second read request queue; a first read request queue is configured for storing and sending a first read request to a memory controller; the first read request is configured for requesting data from memory and storing the data in the memory controller; a number of the first read requests stored in the first read request queue is greater than a number of the plurality of cache lines; the second read request queue is configured for storing and sending a second read request to a memory controller; and the second read request corresponds one-to-one with the first read request, and the second read request is used to request data corresponding to the first read request from the memory controller in the event that a cache line corresponding to the first read request is idle. This cache has higher performance.