Decoded Data Cache Management for Low-Latency Memory Reads
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Solution Overview
Problem
Existing memory systems face performance issues due to cache eviction of imminent data, leading to reduced system performance, as the cache size is limited and future data requests are difficult to predict accurately.
Innovation Solution
A memory device with a decoding module that includes a cache device and decoder, which determines if data is stored in the cache based on decoding latency, and manages cache by storing decoded data or evicting data with high decoding latency to optimize cache usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If data is stored in cache to increase system performance, then data retrieval speed is improved, but cache size is limited and future requests cannot be predicted accurately causing data eviction
Solution Approach 1:
The patent performs preliminary actions by decoding data in advance and storing decoded data in a buffer before it is actually requested. When a read command is received, the system checks if the decoded data is already in the buffer, allowing immediate retrieval without waiting for decoding. This preliminary decoding and buffering action ensures that frequently accessed data is ready for fast retrieval, improving both speed and reliability of data access.
2Reliability
If cache size is increased to store more data, then cache hit rate is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the decoding function from the main data path and performs it in advance on selected data, storing the decoded results in a separate buffer. This extraction allows the system to have a small, efficient buffer for decoded data rather than requiring a large cache for all possible data. The buffer only needs to store decoded data that is likely to be requested, reducing the overall memory requirement while maintaining high cache hit rates for accessed data.
Solution Approach 2:
By performing preliminary decoding and buffering of selected data, the system avoids the need for large cache memory. The buffer stores only the decoded data that is most likely to be requested based on current access patterns, rather than attempting to cache all possible data. This reduces device complexity and cost while maintaining effective cache performance for actual workloads.
3Loss of time
If data is decoded before being requested, then decoding latency is reduced for future requests, but memory bandwidth is consumed for pre-decoding operations
Solution Approach 1:
The patent applies partial action by selectively decoding only certain data that is likely to be requested, rather than decoding all data. The system uses read commands and address information to identify which data to pre-decode and buffer. This partial pre-decoding approach reduces decoding latency for requested data while consuming less memory bandwidth compared to decoding all data, achieving a balanced trade-off between performance and resource usage.
Data Source
AI summary
A memory system includes a system controller and a memory device. The system controller includes a memory controller configured to transmit a received address to a decoding module, and output, to the host device, decoded data. The decoding module includes a cache device and a decoder. The decoding module is configured to receive the data corresponding to the address from the memory device. The decoding module is configured transmit the data stored in the cache device to the memory controller in response to determining that the data corresponding to the address is stored in the cache device. The decoding module is configured to decode the data corresponding to the address to generate decoded data and store the decoded result in the cache device in response to determining that the data corresponding to the address is not stored in the cache device.