xiaoqizhan opened a new pull request, #18767: URL: https://github.com/apache/nuttx/pull/18767
When CONFIG_FS_BACKTRACE is enabled, collecting a stack trace for every new file descriptor adds avoidable overhead to tasks that use only a small number of FDs. Add a dynamic threshold option so backtrace capture is enabled only after the per-task FD count reaches the configured limit. *Note: Please adhere to [Contributing Guidelines](https://github.com/apache/nuttx/blob/master/CONTRIBUTING.md).* ## Summary This patch introduces a dynamic backtrace threshold control mechanism for file descriptors. **Why the change is necessary:** Currently, when `CONFIG_FS_BACKTRACE` is enabled, the system collects a stack backtrace for every newly allocated file descriptor. However, this imposes unnecessary and avoidable performance overhead on tasks that only allocate a small number of file descriptors and never exceed typical limits or experience FD leaks. **What it does and how:** This change introduces `CONFIG_FS_BACKTRACE_DYNAMIC`. When enabled, it avoids capturing stack traces for normal, small-scale file descriptor allocations. The system tracks the number of open file descriptors per task (`fl_open_count`) and only begins filling the backtrace array (`f_backtrace`) once the per-task file descriptor count reaches a configurable threshold (`CONFIG_FS_BACKTRACE_DEFAULT_THRESHOLD`). This feature significantly improves runtime performance for tasks with normal FD usage while still preserving the powerful diagnostic capabilities of `CONFIG_FS_BACKTRACE` for detecting resource leaks when they actually occur. ## Impact * **Users:** Improves runtime performance and reduces system overhead by omitting backtrace collection for tasks that use few file descriptors. * **Build process:** Adds new Kconfig options (`CONFIG_FS_BACKTRACE_DYNAMIC` and `CONFIG_FS_BACKTRACE_DEFAULT_THRESHOLD`). * **Hardware:** None. * **Documentation:** No significant impact, but the Kconfig help text has been updated to reflect the new feature. * **Security:** None. * **Compatibility:** Backward compatible. The dynamic feature defaults to `n`, preserving the original behavior of `CONFIG_FS_BACKTRACE` unless explicitly enabled. ## Testing **Host Machine:** Ubuntu Linux (x86_64) **Target:** Verified on generic simulators and local boards (e.g. `sim:nsh`) **Verification Steps:** 1. Built the system with `CONFIG_FS_BACKTRACE=y` and `CONFIG_FS_BACKTRACE_DYNAMIC=n` to ensure the original backtrace logic works without regression. 2. Built the system with `CONFIG_FS_BACKTRACE_DYNAMIC=y` and set a default threshold (e.g., 60). 3. Created an application that opens multiple files iteratively: * Verified that backtraces are **not** captured for the first 59 file descriptors. * Verified that once the threshold (60th FD) is reached, the `fl_bt_enabled` flag is set, and backtraces are successfully captured and stored for subsequent file descriptors. 4. Verified that file descriptors closed (`fl_open_count` decremented) do not cause the threshold trigger to oscillate incorrectly (once enabled, it stays enabled for that task's fdlist). 5. Tested `fdlist_copy` (task creation) to ensure backtrace thresholds and states are correctly propagated/initialized for child tasks. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
