Impl RRScheduler

src/consts.rs

@@ -1,5 +1,6 @@
 #![allow(dead_code)]
 pub const MAX_CPU_NUM: usize = 8;
+pub const MAX_PROCESS_NUM: usize = 32;
 
 // Copy from Redox consts.rs:
 

src/process/mod.rs

@@ -8,6 +8,7 @@ pub use self::processor::*;
 
 mod process;
 mod processor;
+mod scheduler;
 
 
 pub fn init(mut mc: MemoryController) {

src/process/process.rs

@@ -21,7 +21,7 @@ pub struct Process {
 pub type Pid = usize;
 pub type ErrorCode = usize;
 
-#[derive(Debug, Eq, PartialEq)]
+#[derive(Debug, Clone, Eq, PartialEq)]
 pub enum Status {
     Ready,
     Running,

src/process/processor.rs

@@ -1,6 +1,7 @@
 use alloc::BTreeMap;
 use memory::{ActivePageTable, InactivePageTable};
 use super::process::*;
+use super::scheduler::*;
 use core::cell::RefCell;
 use core::fmt::{Debug, Formatter, Error};
 use util::{EventHub, GetMut2};
@@ -15,6 +16,8 @@ pub struct Processor {
     kernel_page_table: Option<InactivePageTable>,
     /// Choose what on next schedule ?
     next: Option<Pid>,
+    // WARNING: if MAX_PROCESS_NUM is too large, will cause stack overflow
+    scheduler: RRScheduler,
 }
 
 impl Processor {
@@ -22,19 +25,16 @@ impl Processor {
         Processor {
             procs: BTreeMap::<Pid, Process>::new(),
             current_pid: 0,
-            event_hub: {
-                let mut e = EventHub::new();
-                e.push(10, Event::Schedule);
-                e
-            },
+            event_hub: EventHub::new(),
             kernel_page_table: None,
             next: None,
+            scheduler: RRScheduler::new(100),
         }
     }
 
     pub fn set_reschedule(&mut self) {
         let pid = self.current_pid;
-        self.get_mut(pid).status = Status::Ready;
+        self.set_status(pid, Status::Ready);
     }
 
     fn alloc_pid(&self) -> Pid {
@@ -49,9 +49,25 @@ impl Processor {
         return next;
     }
 
+    fn set_status(&mut self, pid: Pid, status: Status) {
+        let status0 = self.get(pid).status.clone();
+        match (&status0, &status) {
+            (&Status::Ready, &Status::Ready) => return,
+            (&Status::Ready, _) => self.scheduler.remove(pid),
+            (_, &Status::Ready) => self.scheduler.insert(pid),
+            _ => {}
+        }
+        trace!("Processor: process {} {:?} -> {:?}", pid, status0, status);
+        self.get_mut(pid).status = status;
+    }
+
     /// Called by timer.
     /// Handle events.
     pub fn tick(&mut self) {
+        let current_pid = self.current_pid;
+        if self.scheduler.tick(current_pid) {
+            self.set_reschedule();
+        }
         self.event_hub.tick();
         while let Some(event) = self.event_hub.pop() {
             debug!("Processor: event {:?}", event);
@@ -61,7 +77,7 @@ impl Processor {
                     self.set_reschedule();
                 },
                 Event::Wakeup(pid) => {
-                    self.get_mut(pid).status = Status::Ready;
+                    self.set_status(pid, Status::Ready);
                     self.set_reschedule();
                     self.next = Some(pid);
                 },
@@ -76,6 +92,9 @@ impl Processor {
     pub fn add(&mut self, mut process: Process) -> Pid {
         let pid = self.alloc_pid();
         process.pid = pid;
+        if process.status == Status::Ready {
+            self.scheduler.insert(pid);
+        }
         self.procs.insert(pid, process);
         pid
     }
@@ -86,17 +105,10 @@ impl Processor {
         if self.current().status == Status::Running {
             return;
         }
-        let pid = self.next.take().unwrap_or_else(|| self.find_next());
+        let pid = self.next.take().unwrap_or_else(|| self.scheduler.select().unwrap());
         self.switch_to(pid);
     }
 
-    fn find_next(&self) -> Pid {
-        *self.procs.keys()
-            .find(|&&i| i > self.current_pid
-                && self.get(i).status == Status::Ready)
-            .unwrap_or(self.procs.keys().next().unwrap())
-    }
-
     /// Switch process to `pid`, switch page table if necessary.
     /// Store `rsp` and point it to target kernel stack.
     /// The current status must be set before, and not be `Running`.
@@ -105,6 +117,9 @@ impl Processor {
         let pid0 = self.current_pid;
 
         if pid == self.current_pid {
+            if self.current().status != Status::Running {
+                self.set_status(pid, Status::Running);
+            }
             return;
         }
         self.current_pid = pid;
@@ -114,6 +129,7 @@ impl Processor {
         assert_ne!(from.status, Status::Running);
         assert_eq!(to.status, Status::Ready);
         to.status = Status::Running;
+        self.scheduler.remove(pid);
 
         // switch page table
         if from.is_user || to.is_user {
@@ -132,8 +148,10 @@ impl Processor {
 
         info!("Processor: switch from {} to {}\n  rsp: ??? -> {:#x}", pid0, pid, to.rsp);
         unsafe {
+            use core::mem::forget;
             super::PROCESSOR.try().unwrap().force_unlock();
             switch(&mut from.rsp, to.rsp);
+            forget(super::PROCESSOR.try().unwrap().lock());
         }
     }
 
@@ -156,16 +174,16 @@ impl Processor {
 
     pub fn exit(&mut self, pid: Pid, error_code: ErrorCode) {
         info!("Processor: {} exit, code: {}", pid, error_code);
-        self.get_mut(pid).status = Status::Exited(error_code);
+        self.set_status(pid, Status::Exited(error_code));
         if let Some(waiter) = self.find_waiter(pid) {
             info!("  then wakeup {}", waiter);
-            self.get_mut(waiter).status = Status::Ready;
+            self.set_status(waiter, Status::Ready);
             self.switch_to(waiter); // yield
         }
     }
 
     pub fn sleep(&mut self, pid: Pid, time: usize) {
-        self.get_mut(pid).status = Status::Sleeping;
+        self.set_status(pid, Status::Sleeping);
         self.event_hub.push(time, Event::Wakeup(pid));
     }
 
@@ -178,7 +196,7 @@ impl Processor {
         let pid = self.try_wait(pid).unwrap_or_else(|| {
             info!("Processor: {} wait for {}", self.current_pid, pid);
             let current_pid = self.current_pid;
-            self.get_mut(current_pid).status = Status::Waiting(pid);
+            self.set_status(current_pid, Status::Waiting(pid));
             self.schedule(); // yield
             self.try_wait(pid).unwrap()
         });

src/process/scheduler.rs

@@ -0,0 +1,93 @@
+use super::*;
+use consts::MAX_PROCESS_NUM;
+
+///
+pub trait Scheduler {
+    fn insert(&mut self, pid: Pid);
+    fn remove(&mut self, pid: Pid);
+    fn select(&self) -> Option<Pid>;
+    fn tick(&mut self, current: Pid) -> bool;   // need reschedule?
+}
+
+pub struct RRScheduler {
+    max_time_slice: usize,
+    infos: [RRProcInfo; MAX_PROCESS_NUM],
+}
+
+#[derive(Debug, Default, Copy, Clone)]
+struct RRProcInfo {
+    present: bool,
+    rest_slice: usize,
+    prev: Pid,
+    next: Pid,
+}
+
+impl Scheduler for RRScheduler {
+    fn insert(&mut self, pid: Pid) {
+        let pid = pid + 1;
+        {
+            let info = &mut self.infos[pid];
+            assert!(!info.present);
+            info.present = true;
+            if info.rest_slice == 0 {
+                info.rest_slice = self.max_time_slice;
+            }
+        }
+        self._list_add_before(pid, 0);
+        trace!("RRScheduler: insert {}", pid - 1);
+    }
+
+    fn remove(&mut self, pid: Pid) {
+        let pid = pid + 1;
+        assert!(self.infos[pid].present);
+        self.infos[pid].present = false;
+        self._list_remove(pid);
+        trace!("RRScheduler: remove {}", pid - 1);
+    }
+
+    fn select(&self) -> Option<Pid> {
+        let ret = match self.infos[0].next {
+            0 => None,
+            i => Some(i - 1),
+        };
+        trace!("RRScheduler: select {:?}", ret);
+        ret
+    }
+
+    fn tick(&mut self, current: Pid) -> bool {
+        let current = current + 1;
+        assert!(!self.infos[current].present);
+
+        let rest = &mut self.infos[current].rest_slice;
+        if *rest > 0 {
+            *rest -= 1;
+        } else {
+            warn!("current process rest_slice = 0, need reschedule")
+        }
+        *rest == 0
+    }
+}
+
+impl RRScheduler {
+    pub fn new(max_time_slice: usize) -> Self {
+        RRScheduler {
+            max_time_slice,
+            infos: [RRProcInfo::default(); MAX_PROCESS_NUM],
+        }
+    }
+    fn _list_add_before(&mut self, i: Pid, at: Pid) {
+        let prev = self.infos[at].prev;
+        self.infos[i].next = at;
+        self.infos[i].prev = prev;
+        self.infos[prev].next = i;
+        self.infos[at].prev = i;
+    }
+    fn _list_remove(&mut self, i: Pid) {
+        let next = self.infos[i].next;
+        let prev = self.infos[i].prev;
+        self.infos[next].prev = prev;
+        self.infos[prev].next = next;
+        self.infos[i].next = 0;
+        self.infos[i].prev = 0;
+    }
+}