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authorIngo Molnar <mingo@elte.hu>2007-07-09 18:51:58 +0200
committerIngo Molnar <mingo@elte.hu>2007-07-09 18:51:58 +0200
commitfa72e9e484c16f0c9aee23981917d8c8c03f0482 (patch)
tree2bcf45d83b9738af2b3455df0e3ada975a100306
parentbb44e5d1c6b3b748e0facf8f516b3162009feb27 (diff)
sched: cfs core, kernel/sched_idletask.c
add kernel/sched_idletask.c - which implements the idle thread scheduling class. This further simplifies sched.c (under CFS), for example a number of 'if (p == rq->idle)' type of special-cases can be removed from sched.c, and schedule() gets simpler too. Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--kernel/sched_idletask.c71
1 files changed, 71 insertions, 0 deletions
diff --git a/kernel/sched_idletask.c b/kernel/sched_idletask.c
new file mode 100644
index 00000000000..41841e741c4
--- /dev/null
+++ b/kernel/sched_idletask.c
@@ -0,0 +1,71 @@
+/*
+ * idle-task scheduling class.
+ *
+ * (NOTE: these are not related to SCHED_IDLE tasks which are
+ * handled in sched_fair.c)
+ */
+
+/*
+ * Idle tasks are unconditionally rescheduled:
+ */
+static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p)
+{
+ resched_task(rq->idle);
+}
+
+static struct task_struct *pick_next_task_idle(struct rq *rq, u64 now)
+{
+ schedstat_inc(rq, sched_goidle);
+
+ return rq->idle;
+}
+
+/*
+ * It is not legal to sleep in the idle task - print a warning
+ * message if some code attempts to do it:
+ */
+static void
+dequeue_task_idle(struct rq *rq, struct task_struct *p, int sleep, u64 now)
+{
+ spin_unlock_irq(&rq->lock);
+ printk(KERN_ERR "bad: scheduling from the idle thread!\n");
+ dump_stack();
+ spin_lock_irq(&rq->lock);
+}
+
+static void put_prev_task_idle(struct rq *rq, struct task_struct *prev, u64 now)
+{
+}
+
+static int
+load_balance_idle(struct rq *this_rq, int this_cpu, struct rq *busiest,
+ unsigned long max_nr_move, unsigned long max_load_move,
+ struct sched_domain *sd, enum cpu_idle_type idle,
+ int *all_pinned, unsigned long *total_load_moved)
+{
+ return 0;
+}
+
+static void task_tick_idle(struct rq *rq, struct task_struct *curr)
+{
+}
+
+/*
+ * Simple, special scheduling class for the per-CPU idle tasks:
+ */
+static struct sched_class idle_sched_class __read_mostly = {
+ /* no enqueue/yield_task for idle tasks */
+
+ /* dequeue is not valid, we print a debug message there: */
+ .dequeue_task = dequeue_task_idle,
+
+ .check_preempt_curr = check_preempt_curr_idle,
+
+ .pick_next_task = pick_next_task_idle,
+ .put_prev_task = put_prev_task_idle,
+
+ .load_balance = load_balance_idle,
+
+ .task_tick = task_tick_idle,
+ /* no .task_new for idle tasks */
+};