Conditional Intervention Circuit for Cache Coherency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In processor-based systems with multiple master devices, maintaining cache coherency is complicated due to different cache line granule sizes and bus coherency protocols, leading to increased intervention latency and power consumption.
Innovation Solution
A conditional intervention circuit is introduced to select the appropriate snooping master device based on cache line granule size and alternate criteria such as shortest path or closest granule size, ensuring efficient data intervention and canceling unnecessary responses to reduce latency and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple snooping master devices provide intervention responses to a read request, then cache coherency is maintained, but intervention latency increases due to the need to select among multiple respondents
Solution Approach 1:
The system performs preliminary actions by having all potential snooping master devices prepare and send intervention responses in advance. The conditional intervention circuit then selects the appropriate response from among these pre-prepared responses, avoiding the need for sequential probing and reducing intervention latency while maintaining cache coherency.
2Reliability
If multiple snooping master devices are allowed to respond to read requests, then cache coherency is ensured, but power consumption increases due to multiple devices actively participating in the transaction
Solution Approach 1:
The invention extracts and identifies only the necessary intervention response from among multiple potential respondents. The conditional intervention circuit determines which snooping master device should actually provide the intervention data based on predetermined criteria, allowing other devices to remain in a lower power state while still maintaining cache coherency through the selective intervention mechanism.
3Adaptability or versatility
If different cache line granule sizes are supported among master devices, then system versatility is improved, but device complexity increases due to the need for conditional selection logic
Solution Approach 1:
The system handles different cache line granule sizes by changing the selection parameters used by the conditional intervention circuit. The circuit compares the granule size parameter of the requesting device with those of potential respondent devices and selects based on matching or compatible size relationships, enabling versatile support for different cache configurations without requiring complex transformation logic.
4Adaptability or versatility
If snooping master devices use different bus coherency protocols, then adaptability is improved, but difficulty of detecting and measuring increases due to protocol variation
Solution Approach 1:
The conditional intervention circuit is designed with universal functionality to handle multiple bus coherency protocols. It implements protocol-agnostic selection criteria that work across different protocol types, allowing the system to maintain cache coherency for devices using various protocols without requiring separate detection and handling logic for each protocol type.
Data Source
AI summary
Maintaining cache coherency using conditional intervention among multiple master devices is disclosed. In one aspect, a conditional intervention circuit is configured to receive intervention responses from multiple snooping master devices. To select a snooping master device to provide intervention data, the conditional intervention circuit determines how many snooping master devices have a cache line granule size the same as or larger than a requesting master device. If one snooping master device has a same or larger cache line granule size, that snooping master device is selected. If more than one snooping master device has a same or larger cache line granule size, a snooping master device is selected based on an alternate criteria. The intervention responses provided by the unselected snooping master devices are canceled by the conditional intervention circuit, and intervention data from the selected snooping master device is provided to the requesting master device.