Storage Command Retry Signaling for Cache-Miss Latency
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Solution Overview
Problem
Existing storage devices experience performance degradation due to varying latencies in accessing different storage media, leading to CPU stalls and inefficient data command processing, especially when cache misses occur.
Innovation Solution
Implementing a storage device with a fast and slow storage medium, along with a response engine that issues a retry message based on estimated latency, allowing the host CPU to manage command buffers more efficiently by removing pending commands and scheduling retries, thereby reducing CPU stalls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If data is stored in slow storage medium (e.g., non-volatile memory), then storage capacity is improved, but access latency increases causing CPU stalls
Solution Approach 1:
The storage device is segmented into two distinct storage mediums: a first storage medium (fast, volatile memory) and a second storage medium (slow, non-volatile memory). Each medium serves specific purposes - the fast medium handles active data access to minimize latency, while the slow medium provides bulk storage capacity. This segmentation allows the system to achieve both high capacity and low latency by directing operations to appropriate mediums.
Solution Approach 2:
The first storage medium (fast volatile memory) acts as an intermediary between the CPU and the second storage medium (slow non-volatile memory). When the CPU needs data, it first checks the fast medium; if not present, the system retrieves from slow medium and pre-loads into fast medium. This intermediary layer buffers the latency difference, preventing CPU stalls while maintaining access to large capacity storage.
2Reliability
If CPU waits for storage device response, then data accuracy is ensured, but CPU utilization decreases causing performance degradation
Solution Approach 1:
The system performs preliminary actions by pre-loading data from the slow storage medium into the fast storage medium before the CPU actually needs it. When data is accessed in the fast medium, the system anticipates future needs and pre-loads related data. This eliminates CPU waiting time while ensuring data accuracy, as all data transfers are completed and verified before CPU access.
Solution Approach 2:
The system implements feedback mechanisms where the storage device provides status messages and latency information back to the CPU. Based on this feedback, the CPU can adjust its command buffer management and retry strategies. This allows the CPU to maintain high utilization by making informed decisions about when to issue commands and when to retry, without compromising data accuracy.
3Productivity
If command buffer is filled with pending commands, then throughput is improved, but saturation risk increases causing performance degradation
Solution Approach 1:
The storage device provides feedback messages to the CPU about command buffer status, processing latency, and saturation risk. Based on this feedback, the CPU dynamically adjusts the rate at which it fills the command buffer, preventing saturation while maintaining high throughput. The feedback loop enables the system to optimize buffer utilization without risking performance degradation from saturation.
Data Source
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AI summary
Systems and methods for data command processing are disclosed. A storage device includes a first storage medium (122), a second storage medium (124), and a processor (120). The processor (120) may be configured to: receive from a computing device (100) a first command associated with first data; search the first storage medium (122) for processing the first command; and based on the search of the first storage medium (122), transmit a message to the computing device (100). Based on a transmission of the message, the storage device may be configured to receive a second command associated with the first data from the computing device (100).