WebSVN – HelenOS-historic – Diff – /kernel/trunk/generic/src/proc/scheduler.c

 #include <typedefs.h>
 #include <cpu.h>
 #include <print.h>
 #include <debug.h>
-atomic_t nrdy;
+static void scheduler_separated_stack(void);
+atomic_t nrdy;  /**< Number of ready threads in the system. */
 /** Take actions before new thread runs.
+ *
  * Perform actions that need to be
  * taken before the newly selected
+ *
  */
 void before_thread_runs(void)
+{
     before_thread_runs_arch();
-#ifdef CONFIG_FPU_LAZY
+    #ifdef CONFIG_FPU_LAZY
     if(THREAD==CPU->fpu_owner)
         fpu_enable();
     else
         fpu_disable();
-#else
+    #else
     fpu_enable();
     if (THREAD->fpu_context_exists)
         fpu_context_restore(&(THREAD->saved_fpu_context));
     else {
         fpu_init(&(THREAD->saved_fpu_context));
         THREAD->fpu_context_exists=1;
+    }
-#endif
+    #endif
+}
-/** Take actions after old thread ran.
+/** Take actions after THREAD had run.
+ *
  * Perform actions that need to be
  * taken after the running thread
- * was preempted by the scheduler.
+ * had been preempted by the scheduler.
+ *
  * THREAD->lock is locked on entry
+ *
  */
 void after_thread_ran(void)
         CPU->fpu_owner->fpu_context_engaged=0;
         spinlock_unlock(&CPU->fpu_owner->lock);
+    }
     spinlock_lock(&THREAD->lock);
-    if (THREAD->fpu_context_exists)
+    if (THREAD->fpu_context_exists) {
         fpu_context_restore(&THREAD->saved_fpu_context);
-    else {
+    } else {
         fpu_init(&(THREAD->saved_fpu_context));
         THREAD->fpu_context_exists=1;
+    }
     CPU->fpu_owner=THREAD;
     THREAD->fpu_context_engaged = 1;
     spinlock_unlock(&THREAD->lock);
     spinlock_unlock(&CPU->lock);
+}
 #endif
 /** Initialize scheduler
  */
 void scheduler_init(void)
+{
+}
 /** Get thread to be scheduled
+ *
  * Get the optimal thread to be scheduled
  * according to thread accounting and scheduler
  * policy.
          goto loop;
+    }
     interrupts_disable();
-    i = 0;
-    for (; i<RQ_COUNT; i++) {
+    for (i = 0; i<RQ_COUNT; i++) {
         r = &CPU->rq[i];
         spinlock_lock(&r->lock);
         if (r->n == 0) {
             /*
              * If this queue is empty, try a lower-priority queue.
         spinlock_lock(&t->lock);
         t->cpu = CPU;
         t->ticks = us2ticks((i+1)*10000);
-        t->priority = i;    /* eventually correct rq index */
+        t->priority = i;    /* correct rq index */
         /*
          * Clear the X_STOLEN flag so that t can be migrated when load balancing needs emerge.
          */
         t->flags &= ~X_STOLEN;
+    }
     goto loop;
+}
 /** Prevent rq starvation
+ *
  * Prevent low priority threads from starving in rq's.
+ *
  * When the function decides to relink rq's, it reconnects
+    }
     spinlock_unlock(&CPU->lock);
+}
+/** The scheduler
+ *
+ * The thread scheduling procedure.
+ * Passes control directly to
+ * scheduler_separated_stack().
+ *
+ */
+void scheduler(void)
+{
+    volatile ipl_t ipl;
+    ASSERT(CPU != NULL);
+    ipl = interrupts_disable();
+    if (atomic_get(&haltstate))
+        halt();
+    if (THREAD) {
+        spinlock_lock(&THREAD->lock);
+        #ifndef CONFIG_FPU_LAZY
+        fpu_context_save(&(THREAD->saved_fpu_context));
+        #endif
+        if (!context_save(&THREAD->saved_context)) {
+            /*
+             * This is the place where threads leave scheduler();
+             */
+            spinlock_unlock(&THREAD->lock);
+            interrupts_restore(THREAD->saved_context.ipl);
+            return;
+        }
+        /*
+         * Interrupt priority level of preempted thread is recorded here
+         * to facilitate scheduler() invocations from interrupts_disable()'d
+         * code (e.g. waitq_sleep_timeout()).
+         */
+        THREAD->saved_context.ipl = ipl;
+    }
+    /*
+     * Through the 'THE' structure, we keep track of THREAD, TASK, CPU, VM
+     * and preemption counter. At this point THE could be coming either
+     * from THREAD's or CPU's stack.
+     */
+    the_copy(THE, (the_t *) CPU->stack);
+    /*
+     * We may not keep the old stack.
+     * Reason: If we kept the old stack and got blocked, for instance, in
+     * find_best_thread(), the old thread could get rescheduled by another
+     * CPU and overwrite the part of its own stack that was also used by
+     * the scheduler on this CPU.
+     *
+     * Moreover, we have to bypass the compiler-generated POP sequence
+     * which is fooled by SP being set to the very top of the stack.
+     * Therefore the scheduler() function continues in
+     * scheduler_separated_stack().
+     */
+    context_save(&CPU->saved_context);
+    context_set(&CPU->saved_context, FADDR(scheduler_separated_stack), (__address) CPU->stack, CPU_STACK_SIZE);
+    context_restore(&CPU->saved_context);
+    /* not reached */
+}
 /** Scheduler stack switch wrapper
+ *
  * Second part of the scheduler() function
  * using new stack. Handling the actual context
  * switch to a new thread.
+ *
  * Assume THREAD->lock is held.
  */
-static void scheduler_separated_stack(void)
+void scheduler_separated_stack(void)
+{
     int priority;
     ASSERT(CPU != NULL);
     if (THREAD) {
-        /* must be run after switch to scheduler stack */
+        /* must be run after the switch to scheduler stack */
         after_thread_ran();
         switch (THREAD->state) {
             case Running:
             THREAD->state = Ready;
+        }
         THREAD = NULL;
+    }
     THREAD = find_best_thread();
     spinlock_lock(&THREAD->lock);
     priority = THREAD->priority;
     spinlock_unlock(&THREAD->lock);
     context_restore(&THREAD->saved_context);
     /* not reached */
+}
-/** The scheduler
- *
- * The thread scheduling procedure.
- * Passes control directly to
- * scheduler_separated_stack().
- *
- */
-void scheduler(void)
-{
-    volatile ipl_t ipl;
-    ASSERT(CPU != NULL);
-    ipl = interrupts_disable();
-    if (atomic_get(&haltstate))
-        halt();
-    if (THREAD) {
-        spinlock_lock(&THREAD->lock);
-#ifndef CONFIG_FPU_LAZY
-        fpu_context_save(&(THREAD->saved_fpu_context));
-#endif
-        if (!context_save(&THREAD->saved_context)) {
-            /*
-             * This is the place where threads leave scheduler();
-             */
-            spinlock_unlock(&THREAD->lock);
-            interrupts_restore(THREAD->saved_context.ipl);
-            return;
-        }
-        /*
-         * Interrupt priority level of preempted thread is recorded here
-         * to facilitate scheduler() invocations from interrupts_disable()'d
-         * code (e.g. waitq_sleep_timeout()).
-         */
-        THREAD->saved_context.ipl = ipl;
-    }
-    /*
-     * Through the 'THE' structure, we keep track of THREAD, TASK, CPU, VM
-     * and preemption counter. At this point THE could be coming either
-     * from THREAD's or CPU's stack.
-     */
-    the_copy(THE, (the_t *) CPU->stack);
-    /*
-     * We may not keep the old stack.
-     * Reason: If we kept the old stack and got blocked, for instance, in
-     * find_best_thread(), the old thread could get rescheduled by another
-     * CPU and overwrite the part of its own stack that was also used by
-     * the scheduler on this CPU.
-     *
-     * Moreover, we have to bypass the compiler-generated POP sequence
-     * which is fooled by SP being set to the very top of the stack.
-     * Therefore the scheduler() function continues in
-     * scheduler_separated_stack().
-     */
-    context_save(&CPU->saved_context);
-    context_set(&CPU->saved_context, FADDR(scheduler_separated_stack), (__address) CPU->stack, CPU_STACK_SIZE);
-    context_restore(&CPU->saved_context);
-    /* not reached */
-}
 #ifdef CONFIG_SMP
 /** Load balancing thread
+ *
  * SMP load balancing thread, supervising thread supplies
  * for the CPU it's wired to.
     link_t *cur;
     /* We are going to mess with scheduler structures,
      * let's not be interrupted */
     ipl = interrupts_disable();
-    printf("*********** Scheduler dump ***********\n");
+    printf("Scheduler dump:\n");
     for (cpu=0;cpu < config.cpu_count; cpu++) {
         if (!cpus[cpu].active)
             continue;
         spinlock_lock(&cpus[cpu].lock);
-        printf("cpu%d: nrdy: %d needs_relink: %d\n",
+        printf("cpu%d: nrdy: %d, needs_relink: %d\n",
                cpus[cpu].id, atomic_get(&cpus[cpu].nrdy), cpus[cpu].needs_relink);
         for (i=0; i<RQ_COUNT; i++) {
             r = &cpus[cpu].rq[i];
             spinlock_lock(&r->lock);
             if (!r->n) {
                 spinlock_unlock(&r->lock);
                 continue;
+            }
-            printf("\tRq %d: ", i);
+            printf("\trq[%d]: ", i);
             for (cur=r->rq_head.next; cur!=&r->rq_head; cur=cur->next) {
                 t = list_get_instance(cur, thread_t, rq_link);
                 printf("%d(%s) ", t->tid,
                        thread_states[t->state]);
+            }

Subversion Repositories HelenOS-historic

(root)/kernel/trunk/generic/src/proc/scheduler.c – Rev 897 → 898