Context Information Translation Cache for Virtualization
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Solution Overview
Problem
In systems supporting virtualization, the frequent remapping of context information between different execution contexts leads to performance issues due to the need for frequent exceptions and traps to the supervisor process, which increases latency and overhead.
Innovation Solution
A context information translation cache is implemented to store mappings between untranslated and translated context information, allowing the lookup circuitry to perform content-addressable memory lookups to reduce the number of traps required, thereby improving performance by caching multiple mappings and minimizing the need for supervisor intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If frequent remapping of context information is performed to support virtualization, then virtualization capability is improved, but trap frequency to supervisor process increases and performance deteriorates
Solution Approach 1:
The patent pre-establishes multiple context information translation entries in the translation cache before they are needed. When context information needs to be remapped, the system checks the translation cache first to see if a translation entry already exists. This preliminary preparation reduces the need for frequent traps to the supervisor process during actual remapping operations, thereby improving performance while maintaining virtualization capability.
Solution Approach 2:
The patent creates translation copies of context information mappings and stores them in the translation cache. Instead of directly remapping context information through supervisor intervention every time, the system generates translation entries that copy the mapping relationship and stores them in advance. This allows the system to use these pre-copied translation entries for subsequent remapping operations without requiring supervisor process involvement, thus reducing trap frequency and improving performance.
2Productivity
If context information translation cache is implemented to reduce traps, then performance is improved, but device complexity increases
Solution Approach 1:
The patent integrates the translation cache structure within the existing processor architecture, nesting it as a component within the supervisor process or memory management unit. The translation cache is organized with an array structure where translation entries are stored in a compact manner, with fields for untranslated context information, translated context information, and valid indicators. This nested organization reduces the overall system complexity compared to implementing a separate, standalone translation mechanism.
Solution Approach 2:
The translation cache acts as an intermediary structure between the context information and the supervisor process. Instead of direct interaction between the remapping operation and the supervisor process, the translation cache mediates by storing pre-prepared translation entries. This intermediary structure simplifies the interaction protocol and reduces the complexity of supervisor intervention, as the system can autonomously retrieve translations from the cache without complex supervisor process involvement.
Data Source
AI summary
A context-information-dependent instruction causes a context-information-dependent operation to be performed based on specified context information indicative of a specified execution context. A context information translation cache 10 stores context information translation entries each specifying untranslated context information and translated context information. Lookup circuitry 14 performs a lookup of the context information translation cache based on the specified context information, to identify whether the context information translation cache includes a matching context information translation entry which is valid and which specifies untranslated context information corresponding to the specified context information. When the matching context information translation entry is identified, the context-information-dependent operation is performed based on the translated context information specified by the matching context information translation entry.