Descriptor-Based Interrupt Mechanism for Storage Read Latency
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Solution Overview
Problem
Data storage devices face delays in processing read requests due to buffering issues when subsequent read operations are not scheduled, leading to prolonged cache states and deteriorated latency characteristics.
Innovation Solution
The data storage device includes a descriptor generation unit and a memory controller that manage descriptors for read and cache output commands, allowing for simultaneous read and cache output operations and enabling the transmission of cache output commands without subsequent read commands when necessary, thereby preventing data from being stuck in buffers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If data is buffered in the nonvolatile memory device for subsequent read operations, then read operations can be performed faster, but data remains stuck in buffers when subsequent reads are not scheduled, increasing latency
Solution Approach 1:
The system uses an interrupt mechanism where the memory controller automatically generates an interrupt to the descriptor generation unit when a read operation is complete, enabling the descriptor generation unit to autonomously determine whether to issue cache output commands without continuous polling, thus reducing latency while maintaining buffer efficiency
Solution Approach 2:
The interrupt mechanism provides feedback from the memory controller to the descriptor generation unit about the completion status of read operations, enabling dynamic decision-making about whether to output cached data based on actual system state rather than static buffering policies
2Productivity
If the system waits for subsequent read commands before outputting cached data, then buffer utilization is maximized, but read performance deteriorates due to prolonged cache states
Solution Approach 1:
The system dynamically adjusts buffer output timing based on real-time conditions: when interrupts indicate no subsequent read is scheduled, cache output commands are issued immediately; when reads are scheduled, data remains buffered. This dynamic behavior optimizes both throughput and latency based on actual workload patterns
Data Source
AI summary
A data storage device includes a controller including a descriptor generation unit suitable for generating a descriptor and a memory controller suitable for generating a command based on the descriptor; and a nonvolatile memory device including a cell region, and suitable for reading first data from the cell region and buffering the first data in response to a first read command transmitted from the memory controller and outputting the first data to the controller in response to a first cache output command transmitted from the memory controller. The descriptor generation unit transmits an interrupt descriptor to the memory controller. The memory controller generates an interrupt to the descriptor generation unit based on the interrupt descriptor, and transmits the first cache output command to the nonvolatile memory device according to an instruction of the descriptor generation unit for the interrupt.