Use linked list in RRScheduler

[Mivik]

Description

The current round-robin scheduler uses a VecDeque to store ready tasks, which is inefficient because all required operations can be performed in constant time using a linked list. This PR replaces VecDeque with linked_list_r4l::List, thereby enhancing the scheduler's theoretical performance.

Backward compatibility

The public interface remains unchanged.

[Copilot]

Pull request overview

This PR optimizes the Round-Robin scheduler by replacing VecDeque with an intrusive linked list (linked_list_r4l::List), improving theoretical performance from O(n) to O(1) for task removal operations. The implementation follows the same pattern used by FifoScheduler in the codebase.

Key Changes

• Added intrusive linked list support to RRTask by introducing a links field and implementing the GetLinks trait
• Replaced VecDeque with linked_list_r4l::List in RRScheduler's ready queue
• Simplified remove_task implementation from O(n) iteration to O(1) linked list removal

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[AsakuraMizu]

You may provide a benchmark result for old VecDeque, intrusive-collections and this one.

[equation314]

Please wait for arceos-org/linked_list_r4l#5 to be merged.

[AsakuraMizu]

ping @Mivik

[AsakuraMizu]

Perhaps we should release linked_list_r4l version 0.3.0 (maybe?) first.

[Mivik]

Yes, a version bump of linked_list_r4l is desired @equation314

[AsakuraMizu]

@Mivik linked_list_r4l 0.3.0 is released now.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.