Sparse Superline Removal in Sectored Cache via Replacement Tracker
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Sectored caches face inefficiencies due to sparsely used superlines occupying valuable cache space for extended periods, as existing eviction strategies lack consideration for occupancy levels and exact age, leading to suboptimal resource utilization.
Innovation Solution
Implementing a replacement tracker (RT) within the cache controller to monitor sector usage and age of superlines, using watermarks to trigger early eviction of sparsely used and aged superlines, thereby optimizing cache capacity and reducing buffering needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a complete superline is evicted from sectored cache, then cache space is freed for new data, but valuable cache space is lost when only a small portion of the superline is actually used
Solution Approach 1:
The patent segments the superline eviction decision into two independent dimensions: occupancy level (how many sectors are used) and age (how long the superline has been in cache). This allows the system to evaluate each superline individually based on its actual usage pattern rather than treating all superlines uniformly, enabling selective eviction of only those superlines that are both sparsely used and old, thereby avoiding waste of cache space while maintaining efficient utilization.
Solution Approach 2:
The patent introduces two new parameters for superline evaluation: occupancy level (number of used sectors) and age (time in cache). By changing the eviction criteria from a single dimension (LRU based on access time) to multiple dimensions (occupancy + age), the system can identify and evict sparsely used superlines that would otherwise remain in cache indefinitely, thus reducing cache space waste while improving overall utilization efficiency.
2Volume of stationary object
If sparsely used superlines are retained in cache, then cache capacity is maintained, but cache space is occupied without much benefit for extended periods
Solution Approach 1:
The patent performs preliminary evaluation of superlines using occupancy and age parameters before eviction decisions are made. By pre-identifying superlines that are both sparsely used (low occupancy) and old (high age), the system can proactively evict them before they continue to occupy cache space unnecessarily, thus reducing the time cache space is occupied without benefit while maintaining overall cache capacity for useful data.
3Ease of operation
If existing eviction strategies are used without considering occupancy levels, then eviction process is simple, but resource utilization becomes suboptimal
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors two key parameters: occupancy level (how many sectors in the superline are actually used) and age (how long the superline has been in cache). This feedback information is used to dynamically adjust eviction decisions, allowing the system to identify sparsely used superlines and evict them preferentially. The feedback loop maintains relatively simple operation while dramatically improving resource utilization by ensuring cache space is allocated to actively used data.
Data Source
AI summary
Provided are an apparatus, system, and method for sparse superline removal. In response to occupancy of a replacement tracker (RT) exceeding an RT eviction watermark, an eviction process is triggered for evicting a superline from a sectored cache storing at least one superline. An eviction candidate is selected from superlines that have: 1) a sector usage below or equal to a superline low watermark and 2) an RT timestamp that is greater than a superline age watermark.