Multi-threaded Polling Device Driver for CPU Utilization
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Solution Overview
Problem
Current device drivers in computer systems face performance and latency issues due to single-threaded operations, especially in non-real-time operating systems, leading to inefficient CPU utilization and unbalanced processor core usage.
Innovation Solution
Implementing a multi-threaded polling device driver that partitions device operations into multiple threads, allowing concurrent control of devices and dynamic adjustment of execution quanta to optimize thread execution and relinquish processor cores, thereby improving performance and reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a device driver is implemented as a single execution thread driven by device interrupts, then the design and implementation is simple, but the performance and latency are poor especially on heavy loaded systems
Solution Approach 1:
The patent divides a single device driver thread into multiple worker threads that can operate concurrently. Each worker thread is assigned to handle specific devices or device groups, allowing parallel processing of interrupt requests and improving overall system performance while maintaining manageable complexity through structured organization
2Loss of time
If a device driver is changed from interrupt driven operation to polling operation, then the latency issue is improved, but the CPU utilization increases decreasing the efficiency of operations when the device is lightly loaded
Solution Approach 1:
The patent implements a hybrid approach where the device driver can dynamically switch between interrupt-driven and polling modes based on system conditions and device activity levels. This allows the system to optimize for low latency when needed while conserving CPU resources during normal operation, resolving the contradiction between latency improvement and CPU efficiency
Solution Approach 2:
The patent modifies operational parameters by introducing configurable polling intervals and interrupt thresholds that can be adjusted based on device criticality and system load. This allows the driver to adapt its behavior to balance latency requirements against CPU utilization, improving efficiency in both lightly and heavily loaded conditions
3Productivity
If a polling device driver is split into multiple threads, then the overhead for polling operation is decreased, but the latency increases
Solution Approach 1:
The patent segments the polling operations into multiple specialized worker threads, each responsible for specific device groups or task types. This segmentation allows parallel execution of polling operations across multiple threads, decreasing overall overhead while maintaining low latency through targeted, efficient polling intervals for each device category
4Loss of time
If a driver thread is pinned to a particular processor core to reduce latency in a multi-core system, then the performance is increased, but the processor core is underutilized and CPU utilization becomes unbalanced
Solution Approach 1:
The patent implements dynamic thread-to-core assignment where driver threads can be migrated between processor cores based on system conditions, device activity patterns, and load balancing requirements. This dynamic assignment allows the system to maintain low latency by keeping critical threads on appropriate cores while simultaneously improving overall CPU utilization by redistributing workloads as conditions change
Solution Approach 2:
The patent designs worker threads with multi-functional capabilities that can handle multiple device types and operation modes. This universality allows a single thread to effectively serve multiple functions across different processor cores, improving core utilization while maintaining the low-latency benefits of dedicated thread assignments when needed
Data Source
AI summary
A polling device driver is partitioned into a plurality of driver threads for controlling a device of a computer system. The device has a first device state of an unscouted state and a scouted state, and a second device state of an inactive state and an active state. A driver thread of the plurality of driver threads determines that the first device state of the device state is in the unscouted state, and changes the first state of the device to the scouted state. The driver thread further determines that the second device state of the device is in the inactive state and changes the second device state of the device to the active state. The driver thread executes an operation on the device during a pre-determined time slot configured for the driver thread.