Atomic Sequence Cache Invalidation for Multi-Core Data Integrity
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Solution Overview
Problem
In multi-core hardware systems, atomic sequences are challenging to implement due to interruptions by other core processors and synchronizing memory caches, leading to potential deadlocks and failures in conditional storing operations.
Innovation Solution
A method involving a core processor initiating an atomic sequence by loading content from a memory location, maintaining a copy, and performing a compare-and-swap operation in cache memory to ensure data integrity and invalidate cache blocks associated with other core processors, preventing interruptions and ensuring successful conditional storing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If atomic sequences are implemented in multi-core hardware systems, then data integrity is improved, but interruptions by other core processors and cache synchronization issues worsen, leading to deadlocks and failures
Solution Approach 1:
The patent introduces a message-passing interface (MPI) as an intermediary layer between core processors and cache memory systems. This mediator handles the complex synchronization and invalidation operations, shielding individual cores from the complexity of multi-cache coordination while ensuring data integrity through standardized communication protocols.
Solution Approach 2:
The system implements feedback mechanisms where cache invalidation status and synchronization states are continuously monitored and communicated back to the executing core processor. This feedback loop allows the system to detect and handle potential deadlocks by providing real-time information about cache state changes and synchronization progress.
2Reliability
If conditional storing operations are performed with compare-and-swap, then data consistency is improved, but the operation complexity and potential for deadlocks worsen
Solution Approach 1:
The system performs preliminary actions by pre-validating cache block states and checking for potential conflicts before executing compare-and-swap operations. This preliminary validation includes verifying cache coherence, checking for pending invalidations, and ensuring no other cores are accessing the same memory location, thereby reducing the likelihood of deadlocks during the actual conditional storing operation.
3Reliability
If cache blocks are invalidated for other core processors, then data integrity is improved, but the time required for synchronization and potential deadlocks worsen
Solution Approach 1:
The patent segments the cache invalidation process into targeted, fine-grained operations rather than broad system-wide invalidations. When a conditional storing operation requires cache invalidation, only the specific cache blocks and sets that are actually affected are invalidated, leaving other caches untouched. This segmentation dramatically reduces the time required for synchronization while maintaining data integrity for the specific memory location being accessed.
Data Source
AI summary
According to at least one example embodiment, a method and corresponding apparatus for conditionally storing data include initiating an atomic sequence by executing, by a core processor, an instruction/operation designed to initiate an atomic sequence. Executing the instruction designed to initiate the atomic sequence includes loading content associated with a memory location into a first cache memory, and maintaining an indication of the memory location and a copy of the corresponding content loaded. A conditional storing operation is then performed, the conditional storing operation includes a compare-and-swap operation, executed by a controller associated with a second cache memory, based on the maintained copy of the content and the indication of the memory location.