Signed-off-by: Gregory Haskins <[email protected]>
---
kernel/vfcipi/thread.c | 144 ++++++++++++++++++++++++++++++++++++++++++++----
1 files changed, 131 insertions(+), 13 deletions(-)
diff --git a/kernel/vfcipi/thread.c b/kernel/vfcipi/thread.c
index 45bb4e2..306560a 100644
--- a/kernel/vfcipi/thread.c
+++ b/kernel/vfcipi/thread.c
@@ -27,6 +27,7 @@
#include <linux/irqflags.h>
#include <linux/module.h>
#include <linux/cpumask.h>
+#include <linux/syscalls.h>
#include <asm/atomic.h>
#include <asm/cmpxchg.h>
@@ -53,9 +54,16 @@ struct vfcipi_queueitem {
struct vfcipi_workitem *item;
};
+struct prio_array {
+ DECLARE_BITMAP(bitmap, MAX_RT_PRIO+1); /* include 1 bit for delimiter */
+ unsigned long count;
+ struct list_head queue[MAX_RT_PRIO];
+};
+
struct vfcipi_task {
raw_spinlock_t lock;
struct task_struct *task;
+ int prio;
struct prio_array rt_rq; /* Real-time request queue */
struct list_head rq; /* Normal request queue */
};
@@ -64,6 +72,67 @@ static DEFINE_PER_CPU(struct vfcipi_task*, vfcipi_tasks);
/*
* ----------------------------------------
+ * prio_array
+ * ----------------------------------------
+ */
+static void prio_array_init(struct prio_array *array)
+{
+ int i;
+
+ memset(array->bitmap, 0, sizeof(array->bitmap));
+ array->count = 0;
+
+ for (i=0; i<MAX_RT_PRIO; i++)
+ INIT_LIST_HEAD(&array->queue[i]);
+}
+
+/* Note: prio_array code credit goes to the RT scheduler...*/
+static struct vfcipi_queueitem* prio_array_dequeue(struct prio_array *array)
+{
+ struct list_head *head;
+ struct vfcipi_queueitem *qi;
+ int idx;
+
+ if (!array->count)
+ return NULL;
+
+ idx = sched_find_first_bit(array->bitmap);
+
+ head = array->queue + idx;
+
+ /* If we got here, there better be something in the list */
+ BUG_ON(!head);
+ BUG_ON(list_empty(head));
+
+ qi = list_first_entry(head, struct vfcipi_queueitem, list);
+ BUG_ON(!qi);
+
+ list_del(&qi->list);
+ array->count--;
+
+ if (list_empty(head))
+ __clear_bit(idx, &array->bitmap);
+
+ return qi;
+}
+
+static void prio_array_enqueue(struct prio_array *array,
+ struct vfcipi_queueitem *qi,
+ int prio)
+{
+ struct list_head *head;
+
+ BUG_ON(prio < 0);
+ BUG_ON(prio > MAX_RT_PRIO);
+
+ head = array->queue + prio;
+ list_add_tail(&qi->list, head);
+ __set_bit(prio, &array->bitmap);
+ array->count++;
+}
+
+/*
+ * ----------------------------------------
* vfcipi_status
* ----------------------------------------
*/
@@ -154,9 +223,33 @@ static void vfcipi_workitem_wait(struct vfcipi_workitem *item, int wait)
* function completes entirely.
*/
vfcipi_status_wait(&item->finished);
+}
+/*
+ * ----------------------------------------
+ * priority-inheritance helpers
+ * ----------------------------------------
+ */
+
+/* Assumes ftask->lock is held */
+static void vfcipi_task_setprio(struct vfcipi_task *ftask, int prio)
+{
+ struct sched_param param = { 0, };
+ pid_t pid = ftask->task->pid;
+
+ if (ftask->prio != prio) {
+ if (prio != -1) {
+ param.sched_priority = prio;
+ sys_sched_setscheduler(pid, SCHED_FIFO, ¶m);
+ } else {
+ sys_sched_setscheduler(pid, SCHED_NORMAL, ¶m);
+ }
+
+ ftask->prio = prio;
+ }
}
+
/*
* ----------------------------------------
* vfcipi_thread - daemon process for vfcipi per CPU
@@ -169,33 +262,48 @@ static int vfcipi_thread(void *data)
while (1) {
struct vfcipi_workitem *item;
- struct vfcipi_queueitem *qi = NULL;
+ struct vfcipi_queueitem *qi;
spin_lock(&ftask->lock);
- if (!list_empty(&ftask->rq)) {
- qi = list_first_entry(&ftask->rq,
- struct vfcipi_queueitem,
- list);
- BUG_ON(!qi);
- list_del(&qi->list);
- }
-
+ /* First check the RT items */
+ qi = prio_array_dequeue(&ftask->rt_rq);
+ if (!qi) {
+ /* If nothing is found there, check the normal queue */
+ if (!list_empty(&ftask->rq)) {
+ qi = list_first_entry(&ftask->rq,
+ struct vfcipi_queueitem,
+ list);
+ BUG_ON(!qi);
+ list_del(&qi->list);
+ }
+ }
+
if (!qi) {
/* Nothing to process for now.. */
+
+ /* Set us back to normal priority */
+ vfcipi_task_setprio(ftask, -1);
+
set_current_state(TASK_INTERRUPTIBLE);
spin_unlock(&ftask->lock);
schedule();
continue;
}
+ item = qi->item;
+
+ /*
+ * Adjust the priority of our task based on what was pulled
+ * from the queue. In theory, its our highest priority item
+ */
+ vfcipi_task_setprio(ftask, item->prio);
+
spin_unlock(&ftask->lock);
/*
- * Extract the real pointer and discard the queueitem shell.
- * We no longer need it.
+ * Discard the shell since the item is already extracted.
*/
- item = qi->item;
vfcipi_heap_free(qi);
/*
@@ -235,7 +343,15 @@ static int vfcipi_enqueue(struct vfcipi_workitem *item, int cpu)
spin_lock(&ftask->lock);
- list_add_tail(&qi->list, &ftask->rq);
+ if (rt_task(current)) {
+ item->prio = current->rt_priority;
+ prio_array_enqueue(&ftask->rt_rq, qi, item->prio);
+
+ /* Priority inheritance on the kthread */
+ if (ftask->prio < item->prio)
+ vfcipi_task_setprio(ftask, item->prio);
+ } else
+ list_add_tail(&qi->list, &ftask->rq);
wake_up_process(ftask->task);
@@ -346,6 +462,8 @@ int __init vfcipi_init(void)
goto out_free;
spin_lock_init(&ftask->lock);
+ ftask->prio = -1;
+ prio_array_init(&ftask->rt_rq);
INIT_LIST_HEAD(&ftask->rq);
per_cpu(vfcipi_tasks, cpu) = ftask;
-
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