scx_rlfifo: replace 1ms sleep with sched_yield()

Small improvement to make the scheduler a bit more responsive, without
introducing too much complexity or too much CPU overhead.

This can be achieved by replacing a sleep of 1ms with a sched_yield()
every time that the scheduler has finished to dispatch all the queued
tasks.

This also makes the code a bit smaller and easier to read.

Signed-off-by: Andrea Righi <andrea.righi@canonical.com>

scheds/rust/scx_rlfifo/src/main.rs

@@ -15,7 +15,7 @@ use std::sync::atomic::AtomicBool;
 use std::sync::atomic::Ordering;
 use std::sync::Arc;
 
-use std::time::{Duration, SystemTime};
+use std::time::SystemTime;
 
 use anyhow::Result;
 
@@ -46,17 +46,14 @@ impl<'a> Scheduler<'a> {
                     // case we can simply ignore the task.
                     if task.cpu >= 0 {
                         let _ = self.bpf.dispatch_task(&DispatchedTask::new(&task));
-                    }
+
                         // Give the task a chance to run and prevent overflowing the dispatch queue.
                         std::thread::yield_now();
                     }
+                }
                 Ok(None) => {
                     // Notify the BPF component that all tasks have been scheduled and dispatched.
                     self.bpf.update_tasks(Some(0), Some(0));
-
-                    // All queued tasks have been dipatched, add a short sleep to reduce
-                    // scheduler's CPU consuption.
-                    std::thread::sleep(Duration::from_millis(1));
                     break;
                 }
                 Err(_) => {
@@ -64,6 +61,8 @@ impl<'a> Scheduler<'a> {
                 }
             }
         }
+        // All queued tasks have been dipatched, yield to reduce scheduler's CPU consumption.
+        std::thread::yield_now();
     }
 
     fn print_stats(&mut self) {