Cache Partitioning for Bounded Block Allocation
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Solution Overview
Problem
Current cache management systems face inefficiencies in limiting storage space for data with specific properties, leading to increased operational latencies, conflict misses, and reduced power management benefits due to lack of finer control over cache block allocation.
Innovation Solution
Implementing a cache controller that enforces a programmable limit on storage space for data with specific properties, using data structures like bit vectors or tables to manage and allocate space efficiently, and redistributing data across partitions to maintain the limit, even when contention exists.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a cache controller enforces a finer limit on the number of cache blocks with specific properties, then operational latencies are reduced and conflict misses are minimized, but device complexity increases due to additional control logic and data structures
Solution Approach 1:
The patent divides the cache into multiple partitions, with each partition dedicated to storing cache blocks with specific properties (e.g., dirty state, coherence state, ownership state). This segmentation allows independent management of different cache block types, enabling finer control limits to be enforced without requiring complex global control logic. Each partition can be managed separately, reducing the overall complexity of the control system while achieving the goal of limiting cache blocks with specific properties.
Solution Approach 2:
The patent introduces intermediary data structures (such as bit vectors or counters) that act as mediators between the cache controller and the cache partitions. These intermediaries track the number of cache blocks in each partition and enforce the fine-grained limits automatically, reducing the complexity of the control logic by delegating the limiting function to simpler intermediary components.
2Quantity of substance
If the cache allows more cache blocks with specific properties to be stored, then storage utilization increases, but power management efficiency decreases due to longer transition latencies to low-power mode
Solution Approach 1:
By segmenting the cache into partitions based on cache block properties, the patent enables selective management of cache partitions for power management purposes. When transitioning to low-power mode, the system can quickly identify and evict cache blocks from specific partitions that have fine-grained limits, reducing the overall eviction latency while maintaining high storage utilization in other partitions.
Solution Approach 2:
The patent implements preliminary tracking of cache block counts in each partition using data structures such as bit vectors or counters. This preliminary action allows the cache controller to proactively identify which cache blocks need to be evicted before a power management transition is requested, significantly reducing the actual transition latency to low-power mode while maintaining high storage utilization.
3Ease of operation
If a cache replacement algorithm does not distinguish requests associated with specific cache properties, then allocation simplicity is maintained, but cache performance degrades due to increased conflict misses
Solution Approach 1:
The patent segments the cache into property-based partitions, which simplifies the allocation strategy by providing clear boundaries for different cache block types. The cache replacement algorithm can then operate independently within each partition, maintaining simplicity while improving performance by preventing cache blocks with specific properties from competing with other types, thereby reducing conflict misses.
Solution Approach 2:
The patent applies local quality by allowing different allocation strategies to be applied to different partitions based on their specific properties. Each partition can have optimized allocation behavior tailored to its cache block type, improving overall cache hit rate while maintaining simple allocation logic within each local partition.
Data Source
AI summary
A system and method for efficiently limiting storage space for data with particular properties in a cache memory. A computing system includes a cache and one or more sources for memory requests. In response to receiving a request to allocate data of a first type, a cache controller allocates the data in the cache responsive to determining a limit of an amount of data of the first type permitted in the cache is not reached. The controller maintains an amount and location information of the data of the first type stored in the cache. Additionally, the cache may be partitioned with each partition designated for storing data of a given type. Allocation of data of the first type is dependent at least upon the availability of a first partition and a limit of an amount of data of the first type in a second partition.