Network Adaptor Interrupt Reduction via Periodic Polling
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Solution Overview
Problem
The IBM System z mainframe's Open Systems Adaptor (OSA) introduces latency due to interrupts and high interrupt frequency, particularly in managing high data rates across numerous host connections, leading to significant delays in data processing.
Innovation Solution
A method is implemented to optimize network adaptor performance by building an outbound buffer list, adding data to a queue, signaling the adaptor with a notification, and employing an extended polling approach to reduce interrupt frequency and latency, allowing the network adaptor to poll for additional data without immediate SIGA-w signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If interrupts are used to notify the host for each data transmission event, then data transmission responsiveness is improved, but latency increases due to heavy interrupt frequency and processing overhead
Solution Approach 1:
The patent implements periodic polling by the network adaptor at predetermined time intervals instead of using interrupt-driven communication. The adaptor periodically checks for outgoing data in buffers and transmits data when available, eliminating the need for frequent interrupts while maintaining responsive data transmission. This periodic action reduces interrupt frequency and associated latency.
Solution Approach 2:
The network adaptor autonomously polls for outgoing data and performs transmission without requiring host processor intervention for each data event. The adaptor self-manages the transmission process by checking buffers periodically and initiating transmissions independently, reducing host processor burden and interrupt overhead while maintaining transmission responsiveness.
2Productivity
If the network adaptor polls for additional outgoing data at predetermined time intervals, then interrupt frequency is reduced, but data transmission delay may increase
Solution Approach 1:
The polling interval is dynamically adjusted based on system conditions and data availability. When data is readily available in buffers, shorter polling intervals ensure rapid transmission. When buffers are empty or data generation is slow, polling intervals extend automatically. This dynamic adjustment optimizes both interrupt reduction and transmission delay minimization.
Solution Approach 2:
The patent changes the polling parameter (time interval) adaptively rather than using a fixed interval. The polling frequency is modified based on observed data patterns, buffer states, and network conditions, allowing the system to reduce interrupts during low-activity periods while maintaining low latency during high-activity periods through parameter optimization.
Data Source
AI summary
A method and system are disclosed for network adaptor optimization and interrupt reduction. The method may also build an outbound buffer list based on outgoing data and add the outgoing data to an outbound buffer queue. Furthermore, the method may set a buffer state from an empty state to a primed state to indicate that the outgoing data is prepared for transmitting and signal a network adaptor with a notification signal.