Dynamic Translation Lookaside Buffer Page Size Configuration
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Solution Overview
Problem
Existing translation lookaside buffers (TLBs) are inflexible and designed for specific memory page sizes, leading to inefficiencies and increased TLB misses when handling applications with different page sizes, limiting system performance and memory addressing capabilities.
Innovation Solution
A method to dynamically configure TLBs to support different memory page sizes by determining the number of lower-order bits for addressing memory locations and reconfiguring the TLB to use higher-order bits for lookups, allowing for on-the-fly changes in page size based on application needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If TLBs are designed for specific memory page sizes, then the TLB structure can be optimized for that particular page size, but the TLB cannot efficiently handle applications with different page sizes, leading to increased TLB misses
Solution Approach 1:
The patent implements dynamic reconfiguration of the TLB by allowing the page size to be changed programmatically through configuration registers. The TLB can switch between different page sizes (e.g., 4KB, 2MB, 1GB) based on application requirements, making the previously static TLB structure adaptive to varying workload demands. This dynamic capability resolves the contradiction by enabling the TLB to maintain optimized performance for the currently active page size while remaining versatile across multiple page size configurations.
Solution Approach 2:
The patent changes the operational parameters of the TLB by introducing configurable page size selections that modify how address bits are interpreted and mapped. By allowing the page size parameter to be changed at runtime through software control, the system can optimize TLB behavior for different workloads without requiring separate dedicated TLBs for each page size, thus improving both efficiency and adaptability.
2Quantity of substance
If a TLB is configured with a large number of entries for small page sizes, then it can address more memory locations for 4KB pages, but it has insufficient entries for large page sizes like 1GB, causing TLB misses
Solution Approach 1:
The patent makes the TLB universal by enabling it to function effectively for multiple page size configurations using the same physical hardware structure. Through programmable configuration, a single TLB can be adapted to handle 4KB, 2MB, 1GB, or other page sizes by reconfiguring the address bit mapping. This multi-functionality allows the TLB to serve diverse application needs without requiring separate specialized TLBs for each page size category.
Solution Approach 2:
The TLB transitions from a static entry-configuration to a dynamic one where the effective number of addressable entries changes based on the selected page size. When configured for large page sizes, the same physical TLB entries can address larger memory regions, effectively increasing the coverage area without adding physical entries. This dynamic adaptation resolves the quantity-versus-versatility contradiction.
3Device complexity
If the TLB structure is fixed for a particular page size, then hardware design is simpler, but the system cannot reconfigure TLBs on-the-fly as application needs change
Solution Approach 1:
The patent introduces dynamic reconfiguration capability to the TLB hardware by incorporating configuration registers and control logic that allow page size to be changed at runtime. The address bit mapping and TLB entry structure can be dynamically adjusted based on the selected page size, enabling the system to adapt to different application requirements without redesigning the hardware for each scenario. This maintains relative hardware simplicity while adding flexibility.
Solution Approach 2:
The patent enables parameter changes in the TLB operation by allowing the page size configuration to be modified through software control. The system can switch between different operational parameters (page sizes) without changing the fundamental hardware architecture, achieving adaptability through configurable parameters rather than through complex reconfigurable hardware structures.
Data Source
AI summary
An example method includes receiving a request to change a page size managed by a translation lookaside buffer (TLB), wherein the TLB is currently managing a first page size, and the request specifies a second page size different than the first page size; in response to the request: determining a number of lower-order bits for addressing memory location within pages of the second page size; and configuring the TLB to perform lookups within the memory subsystem using a number of higher-order bits for addressing pages of the second page size, wherein the number of higher-order bits is dependent on the number of lower-order bits.