Page Fault Handling via Predefined Bit Patterns in Page Tables
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Solution Overview
Problem
Existing data processing systems lack efficient and process-specific handling of page faults, which are common events indicating the need for increased virtual memory, as they often rely on generic operating system handling mechanisms.
Innovation Solution
A data processing apparatus and method that utilize a processor with a page fault handler to detect predefined bit patterns in the page table, allowing for thread-specific page fault operations, including termination, scheduling, and prioritization, and enabling rapid processing by storing indicators in processor registers, such as the Exception Syndrome Register.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If generic operating system handling mechanisms are used for page faults, then system simplicity is maintained, but page fault handling efficiency and process-specific optimization are reduced
Solution Approach 1:
The patent segments page fault handling into multiple categories by using different bit patterns in page table entries. Each bit pattern corresponds to a specific page fault operation, allowing the system to differentiate between various types of page faults (e.g., soft page faults, hard page faults, process-specific faults) and handle them appropriately, thereby improving handling efficiency without requiring a completely new generic mechanism.
Solution Approach 2:
The patent applies local quality by making page fault handling process-specific and thread-specific through the use of bit patterns in page table entries. Different processes or threads can have different bit patterns assigned to their page table entries, enabling customized handling strategies for different workloads or priority levels, thus optimizing performance for specific local conditions rather than using a uniform approach.
2Adaptability or versatility
If predefined bit patterns are used in page tables for process-specific handling, then page fault handling flexibility is improved, but page table structure complexity increases
Solution Approach 1:
The patent uses preliminary action by pre-defining bit patterns in page table entries before page faults occur. These bit patterns are set in advance to indicate the desired page fault operation, so when a page fault occurs, the system can immediately recognize the predefined pattern and execute the corresponding operation without needing to analyze the fault context, thereby improving adaptability while keeping the mechanism straightforward.
Solution Approach 2:
The patent changes parameters by utilizing specific bits or bit combinations in page table entries as indicators for different page fault operations. By modifying the state of these bits (e.g., setting bit 0 to 1 for a soft page fault, or using different bit combinations for different operations), the system encodes multiple handling instructions within the existing page table structure, enhancing versatility without fundamentally altering the page table architecture.
3Speed
If rapid processing by storing indicators in processor registers is implemented, then page fault processing speed is improved, but processor register usage complexity increases
Solution Approach 1:
The patent extracts the page fault operation indicator from the page table and stores it directly in a processor register when a page fault occurs. This extraction allows the page fault handler to immediately access the required operation information from the register without needing to re-examine the page table or perform additional lookups, significantly speeding up processing while isolating the complexity to a single register storage operation.
Solution Approach 2:
The processor register acts as an intermediary between the page table and the page fault handler. Instead of the handler directly parsing page table entries or the handler being tightly coupled with page table structures, the register serves as a buffer that holds the essential operation indicator, simplifying the interaction and enabling rapid processing by decoupling the components.
Data Source
AI summary
A data processing apparatus is provided, comprising a processor configured to execute a process, in particular with at least one thread, a memory management unit component configured to access a page table, and a page fault handler configured to handle page faults by triggering a page fault in response to detecting one of a plurality of predefined bit patterns in the page table, and by assigning a different page fault operation for the process, in particular with the at least one thread, to each of the plurality of predefined bit patterns.