sched: replace sync pause with async pause for setpriority

[hujun260]

Summary

In the kernel, we are planning to remove all occurrences of up_cpu_pause as one of the steps to simplify the implementation of critical sections. The goal is to enable spin_lock_irqsave to encapsulate critical sections, thereby facilitating the replacement of critical sections(big lock) with smaller spin_lock_irqsave(small lock)

Impact

setpriority

Testing

Configuring NuttX and compile:
$ ./tools/configure.sh -l qemu-armv8a:nsh_smp
$ make
Running with qemu
$ qemu-system-aarch64 -cpu cortex-a53 -smp 4 -nographic -machine virt,virtualization=on,gic-version=3
-net none -chardev stdio,id=con,mux=on -serial chardev:con -mon chardev=con,mode=readline -kernel ./nuttx

[nuttxpr]

[Experimental Bot, please feedback here]

The provided PR information does not meet the NuttX Requirements. Here's why and what's missing:

Missing Information:

• Summary:
  • What functional part of the code is being changed? Be specific. Mention the files, functions, or modules affected by the removal of up_cpu_pause.
  • How does the change exactly work? Provide a technical explanation of how removing up_cpu_pause contributes to simplifying critical sections and enabling spin_lock_irqsave.
• Impact:
  • The word "setpriority" seems out of place. You need to systematically address all impact points:
    • Is new feature added? Is existing feature changed? Clarify if this is purely an internal refactoring or if it impacts user-facing functionality.
    • Impact on user: Will any application code using NuttX APIs or behavior be affected?
    • Impact on build: Will any build system changes be required (new configs, dependencies)?
    • Impact on hardware: Are any architectures or boards specifically affected?
    • Impact on documentation: Does any documentation need updates due to code changes or the removal of up_cpu_pause?
    • Impact on security: Could this change introduce any potential security vulnerabilities?
    • Impact on compatibility: Will this affect compatibility with older NuttX versions, applications, or drivers?
• Testing:
  • Build Host(s): Specify the operating system, CPU architecture, and compiler used for building NuttX.
  • Target(s): Be specific about the target architecture (qemu-armv8a is a good start) and the NuttX configuration used (nsh_smp).
  • Testing logs before change: Provide actual logs demonstrating the behavior before your change.
  • Testing logs after change: Provide logs demonstrating how the behavior is different or improved after your change. The logs should showcase the impact of removing up_cpu_pause.

Recommendations:

1. Expand on the technical details: Clearly explain the role of up_cpu_pause and how its removal achieves the stated goals.
2. Thoroughly address impact: Consider all potential consequences of the change, even if the answer is "NO" – provide a brief justification.
3. Provide concrete testing evidence: Include relevant log snippets that demonstrate the change's effect.

By providing comprehensive information, you'll make it easier for reviewers to understand and approve your PR.