I/O Adapter Event Notification Coalescing MSI Requests

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Solution Overview

Problem

Current computing environments face inefficiencies in managing interruption requests from adapters, particularly in converting message signaled interruptions (MSI) into effective I/O adapter event notifications, leading to increased latency and resource utilization issues.

Innovation Solution

A method and system that convert MSI requests into I/O adapter event notifications by using adapter interruption bit vectors and summary bits, allowing multiple MSI requests to be coalesced into a single interruption, thereby optimizing resource usage and reducing latency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple MSI vectors are used to handle adapter events, then event notification capability is improved, but CPU interruption vector consumption increases

Engineering Contradiction:

Improveevent notification capabilityVSAvoidCPU interruption vector consumption

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The patent combines multiple MSI requests into a single I/O adapter event notification by introducing an event notification mechanism that aggregates multiple interruption requests. Instead of each MSI vector generating a separate CPU interruption, multiple MSI requests are merged into one event notification that consumes only one CPU interruption vector, thereby maintaining event notification capability while reducing vector consumption.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces an intermediary event notification mechanism between the adapter and the CPU interruption handler. This intermediary layer receives multiple MSI requests, processes them collectively, and generates a single event notification, thereby reducing the direct mapping between MSI vectors and CPU interruption vectors.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If each MSI request generates a separate interruption, then event processing accuracy is improved, but processing latency increases

Engineering Contradiction:

Improveevent processing accuracyVSAvoidprocessing latency

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent merges multiple MSI requests into a single event notification while preserving the individual event information within the notification structure. This allows the system to process events with appropriate accuracy through the event notification mechanism while reducing latency by avoiding multiple separate interruption handling cycles.

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If multiple CPU interruption vectors are consumed for multiple MSI vectors, then adapter event handling capability is improved, but system resource utilization deteriorates

Engineering Contradiction:

Improveadapter event handling capabilityVSAvoidsystem resource utilization

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent combines multiple MSI requests into a single event notification that maintains the ability to handle diverse adapter events. The event notification structure preserves event-specific information while consolidating the interruption handling, thereby maintaining adapter event handling capability while improving system resource utilization by reducing the number of CPU interruption vectors consumed.

Inventive Principle:

Principle #5Merging (Combining)

4Measurement precision

If multiple MSI requests are handled individually, then interruption processing accuracy is improved, but operating system burden increases

Engineering Contradiction:

Improveinterruption processing accuracyVSAvoidoperating system burden

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges multiple MSI requests into a single event notification while preserving individual event information within the notification structure. This allows the operating system to process events with appropriate accuracy through a unified event notification interface, thereby reducing the burden of handling multiple separate interruptions while maintaining processing accuracy.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentEP2430558B1Converting a message signaled interruption into an I/O adapter event notification

Publication Date: 2015.03.25 INTERNATIONAL BUSINESS MACHINE CORPORATION

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Figure 3A~3B

AI summary

One or more message signaled interruption requests from one or more input/output (I/O) adapters are converted to I/O adapter event notifications. Each I/O adapter event notification includes the setting of one or more specific indicators in system memory and an interruption request, the first of which results in a pending I/O adapter interruption request. While a request for an I/O adapter interruption is pending, subsequent message signaled interruption requests are converted to I/O adapter event notifications, but do not result in additional requests for I/O adapter interruptions.