Variable Nesting Control Parameter for Memory Access Tables
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Solution Overview
Problem
Existing memory management systems face inefficiencies in memory usage and performance when dealing with large address spaces, particularly in multi-level page tables where fixed nesting reduces flexibility in trading off memory footprint against performance.
Innovation Solution
The implementation of a variable nesting control parameter in higher-level access control tables allows dynamic adjustment of the offset portion size for accessing lower-level table entries, enabling flexible trade-offs between memory usage and performance by varying the number of levels traversed in the table structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a multi-level page table structure is used to manage large address spaces, then memory footprint is reduced, but access performance deteriorates due to increased number of table levels to traverse
Solution Approach 1:
The patent implements variable nesting control parameters that allow the number of table levels to be dynamically adjusted based on the specific address space being accessed. Different regions of the address space can have different nesting depths, enabling the system to optimize between memory footprint and access performance on a per-region basis rather than using a fixed global structure.
Solution Approach 2:
The invention changes the parameter of table nesting depth from a fixed value to a variable parameter that can be modified. By storing variable nesting control parameters in higher-level table entries, the system can adjust the number of levels traversed for different address regions, thereby changing the performance-memory footprint tradeoff dynamically without requiring a complete restructuring of the page table.
2Device complexity
If a fixed nesting structure is used for multi-level page tables, then implementation complexity is reduced, but flexibility in trading off memory footprint against performance is lost
Solution Approach 1:
The patent applies local quality by allowing different regions of the address space to have different nesting depths. Instead of a uniform structure, each higher-level table entry can specify a variable nesting control parameter that determines the optimal structure for its corresponding address region. This enables localized optimization without requiring complete redesign of the entire page table system.
Solution Approach 2:
The invention introduces dynamic adjustability through variable nesting control parameters stored in table entries. These parameters allow the page table structure to adapt its nesting depth dynamically based on the specific access requirements, providing flexibility while maintaining a relatively simple base implementation framework.
Data Source
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AI summary
An apparatus (2) has memory management circuitry (16, 20) to control access to a memory system based on access control information defined in table entries of a table structure comprising at least two levels of access control table. Table accessing circuitry (17), (23) accesses the table structure to obtain the access control information corresponding to a target address. For a given access control table at a given level of the table structure other than a starting level, the table accessing circuitry (17, 23) selects a selected table entry of the given access control table corresponding to the target address, based on an offset portion of the target address. A size of the offset portion is selected based on a variable nesting control parameter (190) specified in a table entry of a higher-level access control table at a higher level of the table structure than the given access control table.