!perf: generalize perf syscalls

[adamgreloch]

Previous perf semantics are preserved by passing perf_mode_threads

JIRA: RTOS-1057

Description

Motivation and Context

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Chore (refactoring, style fixes, git/CI config, submodule management, no code logic changes)

How Has This Been Tested?

• Already covered by automatic testing.
• New test added: (add PR link here).
• Tested by hand on: ia32-generic-qemu

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing linter checks and tests passed.
• My changes generate no new compilation warnings for any of the targets.

Special treatment

• This PR needs additional PRs to work (list the PRs, preferably in merge-order).
  !perf: introduce performance analysis subsystem phoenix-rtos-kernel#661
• I will merge this PR by myself when appropriate.

[gemini-code-assist]

Hello @adamgreloch, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

Summary of Changes

Hello! Gemini here, providing a summary of this pull request. The primary goal of this PR, as indicated by the title and changes, is to generalize the performance monitoring (perf) syscalls within the system. Previously, these functions (perf_start, perf_read, perf_finish) were declared within the sys/threads.h header, implying a thread-specific focus. This change introduces a new header file, sys/perf.h, specifically for performance monitoring functions and modifies the function signatures to include a perf_mode_t mode parameter. This allows the perf syscalls to support different modes of operation beyond just threads, making the performance monitoring framework more flexible. The previous thread-specific behavior is preserved by using the perf_mode_threads mode. This is a breaking change as consumers of the old perf_* functions will need to update their includes and function calls.

Highlights

• Generalization of Perf Syscalls: The performance monitoring syscalls (perf_start, perf_read, perf_finish) are generalized to support different modes of operation.
• New Header File: A dedicated header file, include/sys/perf.h, is introduced to house the declarations for performance monitoring functions.
• Mode Parameter Added: The perf_start, perf_read, and perf_finish functions now accept a perf_mode_t mode parameter to specify the desired monitoring mode.
• Removal from sys/threads.h: The old declarations of the perf functions are removed from include/sys/threads.h.
• Breaking Change: This PR is marked as a breaking change, requiring updates for code that previously used the perf functions from sys/threads.h.
• Dependency: This PR requires another PR (phoenix-rtos/phoenix-rtos-kernel/pull/661) to function correctly.

Changelog

• include/sys/perf.h
  • Added a new header file for performance monitoring syscall declarations.
  • Declared perf_start, perf_read, and perf_finish functions with a new perf_mode_t mode parameter.
• include/sys/threads.h
  • Removed the old declarations for perf_start, perf_read, and perf_finish.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point in your pull request via creating an issue comment (i.e. comment on the pull request page) using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in issue comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist is currently in preview and may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments to provide feedback.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

---

Headers shift and change,
Functions find a new home,
Perf modes now expand.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[gemini-code-assist]

Code Review

This pull request successfully generalizes the performance syscall declarations by moving them from include/sys/threads.h to a new dedicated header file include/sys/perf.h and updating their signatures to include a perf_mode_t argument. This is a good step towards better organization and flexibility for performance monitoring features. The removal of the old declarations from sys/threads.h correctly reflects the breaking change mentioned in the description.

It's noted that this PR is dependent on phoenix-rtos/phoenix-rtos-kernel#661 for the corresponding implementation changes. The header changes themselves appear correct and well-structured.

Summary of Findings

• Copyright Year: The copyright year in the new header file include/sys/perf.h is set to 2025. This is likely a typo and should be the current year (2024). This was identified as a low severity issue and not commented on directly per review settings.
• Header Formatting: There are some extra blank lines around function declarations in include/sys/perf.h. While not functionally incorrect, consistent formatting improves readability. This was identified as a low severity issue and not commented on directly per review settings.

Merge Readiness

Based on the review of the header file changes presented in this pull request, no critical or high severity issues were found. The changes correctly introduce a new header for performance syscalls and remove the old declarations, aligning with the PR's goal of generalization. The PR is dependent on a linked kernel PR for the implementation, so the full functionality and impact of the breaking change will depend on that. From the perspective of these header changes alone, the pull request appears ready to be merged, but I am unable to approve it directly. Please have other reviewers approve this code before merging.