Speculative Forward Translation for Emulation Execution Bottlenecks
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Solution Overview
Problem
Just-In-Time (JIT) translation in emulation of a target system on a host system leads to translation loads being placed on the critical execution path, causing execution slowdowns, especially in dynamic environments where translation peaks occur unpredictably.
Innovation Solution
Implementing speculative forward translation by moving the translation load off the critical path through the use of a separate logical execution thread that speculatively translates target system code ahead of execution, allowing translation to occur on different resources or at defined intervals, and incorporating heuristic methods for candidate selection and scheduling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Just-In-Time translation is used to translate target system code during execution, then translation is performed on-demand, but translation loads are placed on the critical execution path causing execution slowdowns
Solution Approach 1:
The patent applies preliminary action by performing speculative forward translation of target system code blocks before they are actually executed. The translation thread anticipates which code blocks will be needed and translates them in advance, storing the translated code in a cache. This eliminates the need to perform translation during the critical execution path, thereby maintaining high execution speed while still achieving efficient translation through advance preparation.
2Adaptability or versatility
If translation is performed on the critical execution path, then translation occurs when code is needed, but unpredictable translation peaks cause execution slowdowns
Solution Approach 1:
The speculative forward translation thread performs preliminary translation of code blocks that are predicted to be executed soon. By translating code in advance based on prediction heuristics rather than waiting for actual execution needs, the system eliminates unpredictable translation peaks during execution while maintaining dynamic adaptability through the prediction-based selection of which code to translate first.
Solution Approach 2:
The patent implements dynamics by using a speculative translation thread that dynamically adjusts which code blocks to translate based on prediction heuristics and current execution state. The translation thread operates independently and can dynamically allocate translation resources to different code blocks based on predicted needs, rather than following a fixed or demand-driven translation schedule.
3Productivity
If a separate translation thread is used for speculative forward translation, then translation load is distributed, but system complexity increases
Solution Approach 1:
The patent applies segmentation by separating the emulation system into distinct functional threads: a main execution thread that runs the emulated program and a separate speculative translation thread that performs code translation. This segmentation allows translation operations to occur independently without blocking execution, improving translation throughput while managing complexity through clear separation of concerns and well-defined thread interfaces.
Data Source
AI summary
A method and apparatus for processor emulation using speculative forward translation are disclosed. A potential candidate for forward translation is identified from one or more portions of target system code. A priority for forward translation is assigned to the potential candidate. It is determined whether the potential candidate is a valid candidate for forward translation. If valid, the potential candidate is translated with a host system to produce one or more corresponding blocks of translated code executable by the host system.