Cache Invalidation via Global Bit Flag
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Solution Overview
Problem
In computing systems with multiple nodes, ensuring data synchronization and preventing stale data readings from caches is challenging, as existing methods can be time-consuming and inefficient, particularly when dealing with large-scale systems where global data values need to be validated and invalidated across nodes.
Innovation Solution
A method and system that utilize a hardware comparator to determine and invalidate cache data values marked as global, using flags within metadata to selectively invalidate cache portions, ensuring that only global data values are updated, and employing global synchronization commands to maintain data coherence across nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If global data values are invalidated across all nodes in multi-node computing systems, then data synchronization reliability is improved, but processing time and system latency increase
Solution Approach 1:
The patent segments the cache invalidation process by introducing a global bit flag that identifies specific cache lines containing global data values. Instead of invalidating entire caches or using complex coordination protocols, the system divides the invalidation task into targeted operations on individual cache lines marked with the global bit, thereby reducing unnecessary invalidation overhead and processing time while maintaining synchronization reliability.
Solution Approach 2:
The patent applies preliminary action by setting the global bit flag in cache line metadata before invalidation is needed. This pre-marking of global data values allows the system to quickly identify and invalidate only the necessary cache lines when synchronization is required, avoiding the time-consuming process of scanning or coordinating invalidation across all cache lines.
2Productivity
If cache invalidation is performed selectively based on global data values, then processing efficiency is improved, but device complexity increases
Solution Approach 1:
The patent extracts the global data identification function into a separate metadata field (the global bit flag) within cache line information. This extraction allows the cache management logic to remain simple while the global bit handles the complexity of identifying global data values, thereby maintaining processing efficiency without significantly increasing overall device complexity.
Solution Approach 2:
The global bit flag acts as an intermediary between the cache storage system and the invalidation control logic. This simple binary flag mediates the complex task of identifying global data values, allowing efficient selective invalidation without requiring complex cache management algorithms or increased device complexity.
3Speed
If hardware comparators are used to determine global data values, then determination speed is improved, but manufacturing cost and device complexity increase
Solution Approach 1:
The patent implements self-service by having the hardware comparator automatically compare incoming memory addresses against cached tag values and check the global bit flag without requiring software intervention. This automated hardware-level operation provides fast determination of global data values while keeping the overall system design simple and avoiding the need for complex control logic.
Solution Approach 2:
The patent replaces software-based cache invalidation determination with a hardware comparator that operates at the circuit level. This substitution of mechanical/software operations with hardware operations provides faster determination speed while the simple global bit flag keeps the hardware complexity manageable.
4Reliability
If all cache portions are invalidated to prevent stale data, then data coherence is improved, but processing productivity decreases
Solution Approach 1:
The patent applies local quality by treating different cache lines differently based on their global bit flag status. Cache lines with the global bit set are invalidated to maintain coherence, while cache lines without the global bit remain valid and are not subjected to invalidation overhead. This localized approach maintains data coherence for global data while preserving processing productivity for local data.
Solution Approach 2:
The patent segments the cache into global and local data portions using the global bit flag. This segmentation allows the system to invalidate only the global data portions when coherence is required, while leaving local data portions untouched and functional, thereby maintaining data coherence without sacrificing overall processing productivity.
Data Source
AI summary
Systems and methods for computing with multiple nodes. In some embodiments, the method includes: determining that a first data value in a cache is a global data value; setting a first flag to indicate that the first data value is a global data value; and selectively invalidating one or more portions of the cache, wherein the selective invalidating of the cache includes: determining, based on the first flag, that the first data value is a global data value; and based on the determining, invalidating the first data value.