Debug Tool Page Fault Swapping for Memory Optimization
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Solution Overview
Problem
Existing debugging tools consume significant memory and time by copying and storing original bytes for all processes, even if not all processes hit the breakpoint instruction, and require specialized code for page management.
Innovation Solution
The method leverages page fault and page reclaim capabilities by marking memory pages for debugging and swapping them out, only loading and modifying pages that contain the debug address during runtime, thus avoiding unnecessary memory copying and using existing page fault and reclaim processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the debug tool copies and stores original bytes for all processes using the file, then the breakpoint instruction can be inserted into all processes, but significant memory is consumed and processing time increases
Solution Approach 1:
The patent applies local quality by making the memory page read-only attribute specific to pages containing the debug address rather than all pages. When the debug tool identifies a page containing the target address, it sets the read-only attribute only for that specific page, allowing selective protection without affecting other pages in the process address space.
Solution Approach 2:
The patent uses preliminary action by pre-setting the read-only attribute on memory pages during the debugging setup phase. Before the application runs, the debug tool identifies pages containing debug addresses and marks them as read-only, so that when page faults occur during execution, the breakpoint can be inserted without requiring additional memory operations or restoring original state.
2Reliability
If the debug tool copies and stores original bytes for all processes, then breakpoints can be set in all processes, but a significant amount of time is spent storing the original bytes
Solution Approach 1:
The patent applies local quality by making the memory page read-only attribute specific to pages containing the debug address rather than all pages. When the debug tool identifies a page containing the target address, it sets the read-only attribute only for that specific page, allowing selective protection without affecting other pages in the process address space.
Solution Approach 2:
The patent uses preliminary action by pre-setting the read-only attribute on memory pages during the debugging setup phase. Before the application runs, the debug tool identifies pages containing debug addresses and marks them as read-only, so that when page faults occur during execution, the breakpoint can be inserted without requiring additional memory operations or restoring original state.
3Adaptability or versatility
If specialized code is used for registering the trap and managing memory pages, then debugging functionality is achieved, but device complexity increases
Solution Approach 1:
The patent applies universality by using the existing page fault mechanism, which is a general operating system feature for memory management, to achieve the specific debugging function of inserting breakpoints. The same page fault handling code serves both normal memory management and debugging purposes, eliminating the need for specialized breakpoint registration code.
Solution Approach 2:
The patent applies self-service by leveraging the operating system's built-in page fault and memory management capabilities to handle breakpoint insertion automatically. When a process accesses a marked page, the OS generates a page fault, which the debug tool's page fault handler processes to insert the breakpoint, eliminating the need for manual intervention or specialized registration code.
4Ease of operation
If memory pages are restored to original state by loading stored original bytes, then debugging capabilities can be turned off, but this process is time consuming and complex
Solution Approach 1:
The patent applies discarding and recovering by using the read-only attribute as a persistent marker that remains on the memory page throughout the debugging session. Instead of storing and restoring original bytes, the debug tool simply clears the read-only attribute when debugging is complete, allowing the page to be naturally restored to its original writable state without explicit restoration operations.
Data Source
AI summary
An exemplary system may include debug capabilities. In one embodiment, the system obtains a debug address. For a process associated with the system, the system determines whether a memory page used by the process includes the debug address. Upon determining that the memory page used by the process includes the debug address, the system marks the memory page for debug and sends the memory page to a swap area.