Separate Read-Only and Write-Read Caches for Memory Subsystems
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Solution Overview
Problem
Conventional memory sub-systems face performance issues due to the use of a single cache for both read and write operations, leading to increased latency and reduced endurance of memory components, especially when handling sequential and random memory access workloads, and data hazards occur when requests are not properly synchronized.
Innovation Solution
Implementing separate read-only and write-read caches with outstanding command queues and a priority scheduler to manage requests, allowing for in-order and out-of-order access based on workload type, reducing the number of requests to the backing store, and improving data throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single cache is used for both read and write operations, then device complexity is reduced, but performance and latency are worsened
Solution Approach 1:
The patent divides the single cache into separate read-only cache and write-read cache structures. This segmentation allows independent optimization of read and write operations, reducing contention and improving access latency for both operation types simultaneously.
2Device complexity
If a single cache is used for both read and write operations, then device complexity is reduced, but endurance of memory components is worsened
Solution Approach 1:
By segmenting the cache into read-only and write-read portions, the patent reduces the number of write operations to the backing store through write-back caching. This decreases wear on memory components and improves their endurance.
3Device complexity
If requests are not properly synchronized, then device complexity is reduced, but data hazards occur
Solution Approach 1:
The patent introduces an intermediary structure (the separate cache hierarchies with priority schedulers) that mediates between read and write requests. This intermediary ensures proper synchronization and ordering of operations, preventing data hazards while maintaining manageable complexity.
4Speed
If separate read-only and write-read caches are implemented, then performance and endurance are improved, but device complexity increases
Solution Approach 1:
The write-read cache is designed to handle both read and write operations, providing multi-functionality that reduces the need for completely separate cache structures. This universal approach improves performance while limiting the increase in complexity.
5Reliability
If separate read-only and write-read caches are implemented, then endurance of memory components is improved, but device complexity increases
Solution Approach 1:
The patent extracts the write-intensive operations into a separate write-read cache hierarchy, isolating them from the read-only cache. This extraction improves endurance by reducing backing store access while organizing complexity into manageable, functional segments.
6Productivity
If in-order and out-of-order access is allowed based on workload type, then productivity is improved, but device complexity increases
Solution Approach 1:
The patent implements dynamic scheduling that adapts to workload characteristics, allowing in-order or out-of-order processing based on conditions. This dynamic approach maximizes throughput while managing complexity through adaptive rather than static control logic.
Data Source
AI summary
A request to read data stored at a memory sub-system can be received. A determination can be made whether the data is stored at a cache of the memory sub-system. responsive to determining that the data is not stored at the cache of the memory sub-system, a determination can be made, by a processing device, of a queue of a set of queues to store the request with other read requests for the data stored at the memory sub-system. Each queue of the et of queues corresponds to a respective cache line of the cache. The request can be stored at the determined queue with the other read requests for the data stored at the memory sub-system.