I/O Scheduler for Solid State Storage Latency Management
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Solution Overview
Problem
Traditional operating system input/output schedulers are not optimized for solid state storage devices, leading to increased apparent latency due to the dominance of write requests in the storage buffer, which starves out read requests and affects overall I/O performance.
Innovation Solution
Implementing an I/O scheduler that monitors and manages the number and timing of write requests to maintain a balance with read requests, and adjusts based on latency thresholds to prevent write requests from overwhelming the storage buffer, thereby ensuring efficient processing of both read and write requests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If write requests are sent directly to solid state storage without scheduling, then the storage buffer can service multiple I/O requests concurrently, but write requests dominate the buffer and starve out read requests, increasing apparent latency
Solution Approach 1:
The I/O scheduler performs preliminary actions by monitoring write request latency before submitting new write requests to the storage buffer. When latency exceeds a threshold, the scheduler proactively limits write request submission to prevent buffer domination, thereby preserving buffer space for read requests and maintaining low apparent latency.
Solution Approach 2:
The system implements feedback control by continuously monitoring the latency of write requests in the storage buffer and using this information to dynamically adjust the rate of write request submission. This feedback mechanism ensures that write requests do not overwhelm the buffer, preventing starvation of read requests and maintaining optimal I/O performance.
2Stability of the object's composition
If traditional I/O schedulers are used with solid state storage, then I/O ordering is maintained, but the schedulers are optimized for magnetic storage and do not account for the faster read speeds and concurrent servicing capabilities of solid state storage
Solution Approach 1:
The patent changes the operational parameters of the I/O scheduler by removing the strict ordering constraints optimized for magnetic storage and adapting to the solid state storage characteristics of faster read speeds and concurrent servicing capabilities. The scheduler monitors latency as a key parameter and adjusts write request submission accordingly, rather than relying on fixed I/O ordering rules.
3Productivity
If the storage buffer accepts a high number of write requests, then write throughput is increased, but read requests are starved out and I/O latency increases
Solution Approach 1:
The I/O scheduler applies partial action by limiting write request submission to a controlled rate based on latency thresholds. Rather than accepting all write requests or using a fixed quota, the scheduler dynamically adjusts the level of write request acceptance, submitting write requests partially based on current buffer conditions to balance write throughput with read request performance.
Data Source
AI summary
An I/O scheduler can manage and schedule write requests that are sent to a storage device in order to prevent the write requests from dominating a storage buffer of the storage device. The I/O scheduler can monitor the number of I/O requests in the storage buffer and maintain a balance between write requests and read requests in the storage buffer. The I/O scheduler monitor the latency of the storage device in processing write requests and manage the write requests sent to the storage device based on the latency. The I/O scheduler can utilize one or more write thresholds. The write thresholds can define thresholds of the number of write requests in the storage buffer and thresholds for the latency of the storage device in processing write requests. The write threshold can represent acceptable levels of write request in the storage buffer and acceptable latency for write requests.