Fix TODO in work stealing scheduler

Cargo.toml

@@ -0,0 +1,9 @@
+[workspace]
+members = [
+    "bootloader",
+    "crate/bit-allocator",
+    "crate/memory",
+    "crate/sync",
+    "crate/thread",
+]
+exclude = ["kernel"]

crate/memory/src/paging/mock_page_table.rs

@@ -54,11 +54,11 @@ impl Entry for MockEntry {
     fn swapped(&self) -> bool { self.swapped }
     fn set_swapped(&mut self, value: bool) { self.swapped = value; }
     fn user(&self) -> bool { unimplemented!() }
-    fn set_user(&mut self, value: bool) { unimplemented!() }
+    fn set_user(&mut self, _value: bool) { unimplemented!() }
     fn execute(&self) -> bool { unimplemented!() }
-    fn set_execute(&mut self, value: bool) { unimplemented!() }
-    fn mmio(&self) -> bool { unimplemented!() }
-    fn set_mmio(&mut self, value: bool) { unimplemented!() }
+    fn set_execute(&mut self, _value: bool) { unimplemented!() }
+    fn mmio(&self) -> u8 { unimplemented!() }
+    fn set_mmio(&mut self, _value: u8) { unimplemented!() }
 }
 
 type PageFaultHandler = Box<FnMut(&mut MockPageTable, VirtAddr)>;

crate/thread/src/scheduler/work_stealing.rs

@@ -17,10 +17,24 @@ impl WorkStealingScheduler {
 
 impl Scheduler for WorkStealingScheduler {
     fn push(&self, tid: usize) {
-        // TODO: push to random queue?
-        // now just push to cpu0
-        self.workers[0].push(tid);
-        trace!("work-stealing: cpu0 push thread {}", tid);
+        // not random, but uniform
+        // no sync, because we don't need to
+        static mut WORKER_CPU: usize = 0;
+        let n = self.workers.len();
+        let mut cpu = unsafe {
+            WORKER_CPU = WORKER_CPU + 1;
+            if WORKER_CPU >= n {
+                WORKER_CPU -= n;
+            }
+            WORKER_CPU
+        };
+
+        // potential racing, so we just check once more
+        if cpu >= n {
+            cpu -= n;
+        }
+        self.workers[cpu].push(tid);
+        trace!("work-stealing: cpu{} push thread {}", cpu, tid);
     }
 
     fn pop(&self, cpu_id: usize) -> Option<usize> {