Interrupt Deferral Instructions for Race Condition Prevention
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Solution Overview
Problem
Concurrent processing in computer systems faces challenges with race conditions and performance overhead due to existing synchronization techniques, such as locking operations, which can lead to unpredictable behavior and reduced application performance.
Innovation Solution
The introduction of interrupt deferral instructions allows applications to defer and re-enable interrupts, enabling efficient protection of critical sections by temporarily disabling interrupt delivery during concurrent access to shared resources, thereby preventing race conditions without the performance overhead of traditional locking methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional locking operations are used to protect critical sections, then race conditions are prevented, but application performance and processing speed deteriorate due to synchronization overhead
Solution Approach 1:
The patent extracts the interrupt handling mechanism from the traditional locking approach. Instead of using software-based locks that require context switches and system calls, the invention directly manipulates the processor's interrupt control bits to achieve critical section protection. This extraction of the core synchronization function (preventing concurrent access) from the complex locking protocol eliminates the performance overhead while maintaining race condition prevention.
Solution Approach 2:
The patent replaces the mechanical/software-based locking system with a hardware-based interrupt control mechanism. By using processor instructions that directly set and clear interrupt enable bits (such as the IF flag in x86 architecture), the system substitutes complex software synchronization protocols with simple hardware control, dramatically reducing synchronization overhead and improving application performance.
2Productivity
If interrupt deferral instructions are used to protect critical sections, then synchronization efficiency improves and latency reduces, but system complexity increases due to interrupt management
Solution Approach 1:
The patent implements self-service interrupt management where the processor automatically handles interrupt queuing and delivery. When interrupts are deferred during critical section execution, the processor hardware automatically queues the interrupted tasks and restores them after the critical section completes. This eliminates the need for application code to manually manage interrupt state, reducing complexity despite the advanced synchronization capability.
3Productivity
If concurrent access to shared resources is allowed without synchronization, then processing speed increases, but system reliability deteriorates due to race conditions
Solution Approach 1:
The patent implements periodic interrupt restoration rather than continuous locking. Instead of maintaining locks throughout the entire processing cycle, the system periodically defers interrupts only during critical section execution and automatically restores them afterward. This periodic approach allows concurrent access during non-critical periods (maintaining high processing speed) while ensuring reliability during critical resource access periods.
Data Source
AI summary
An example method may include responsive to receiving, by a processing device, an interrupt deferral instruction requesting that interrupts be deferred, disabling delivery of interrupts by the processing device, receiving one or more interrupt requests subsequent to disabling delivery of interrupts, and responsive to determining that a deferral termination criterion is satisfied, delivering one or more interrupts, wherein each of the one or more interrupts is specified by a respective one of the interrupt requests. The method may further include receiving a resume interrupt delivery instruction requesting that deferred and subsequent interrupts be delivered, wherein the deferral termination criterion is satisfied in response to receiving the resume interrupt delivery instruction. The method may further include, responsive to receiving the resume interrupt delivery instruction, enabling delivery of the one or more interrupts and subsequent interrupts by the processing device.