Added support for choices in budget policy enforcement.

NO_ENFORCEMENT - A job may execute beyond its declared execution time.
  Jobs notify the kernel that they are complete via liblitmus's
  sleep_next_period()
QUANTUM_ENFORCEMENT - The kernel terminates a job if its actual execution
  time exceeds the declared execution time.
PRECISE_ENFORCEMENT - Hook declared, but not yet implemented.  Plan to
  support this policy through hrtimers.  Error thrown if specified.

6 files changed, 30 insertions, 8 deletions

diff --git a/include/litmus/litmus.h b/include/litmus/litmus.h
index 62107e659c12..d515d1af1096 100644
--- a/include/litmus/litmus.h
+++ b/include/litmus/litmus.h
@@ -83,6 +83,8 @@ inline static int budget_exhausted(struct task_struct* t)
         return get_exec_time(t) >= get_exec_cost(t);
 }
 
+#define budget_enforced(t) (tsk_rt(t)->task_params.budget_policy != NO_ENFORCEMENT)
+
 
 #define is_hrt(t)               \
         (tsk_rt(t)->task_params.class == RT_CLASS_HARD)
diff --git a/include/litmus/rt_param.h b/include/litmus/rt_param.h
index 5b94d1a8eea7..a7a183f34a80 100644
--- a/include/litmus/rt_param.h
+++ b/include/litmus/rt_param.h
@@ -27,12 +27,19 @@ typedef enum {
         RT_CLASS_BEST_EFFORT
 } task_class_t;
 
+typedef enum {
+        NO_ENFORCEMENT,      /* job may overrun unhindered */
+        QUANTUM_ENFORCEMENT, /* budgets are only checked on quantum boundaries */
+        PRECISE_ENFORCEMENT  /* NOT IMPLEMENTED - enforced with hrtimers */
+} budget_policy_t;
+
 struct rt_task {
         lt_t            exec_cost;
         lt_t            period;
         lt_t            phase;
-        unsigned int    cpu;
-        task_class_t    cls;
+        unsigned int    cpu;
+        task_class_t    cls;
+        budget_policy_t budget_policy; /* ignored by pfair */
 };
 
 /* The definition of the data that is shared between the kernel and real-time
diff --git a/litmus/litmus.c b/litmus/litmus.c
index 99714d06eed5..86ad5b375934 100644
--- a/litmus/litmus.c
+++ b/litmus/litmus.c
@@ -112,6 +112,13 @@ asmlinkage long sys_set_rt_task_param(pid_t pid, struct rt_task __user * param)
                        "because wcet > period\n", pid);
                 goto out_unlock;
         }
+        if (tp.budget_policy != NO_ENFORCEMENT &&
+                tp.budget_policy != QUANTUM_ENFORCEMENT)
+        {
+                printk(KERN_INFO "litmus: real-time task %d rejected "
+                        "because unsupported budget enforcement policy specified\n", pid);
+                goto out_unlock;
+        }
 
         target->rt_param.task_params = tp;
 
diff --git a/litmus/sched_cedf.c b/litmus/sched_cedf.c
index 118fbd14fe25..82c9682eefbd 100644
--- a/litmus/sched_cedf.c
+++ b/litmus/sched_cedf.c
@@ -321,7 +321,7 @@ static noinline void job_completion(struct task_struct *t, int forced)
  */
 static void cedf_tick(struct task_struct* t)
 {
-        if (is_realtime(t) && budget_exhausted(t)) {
+        if (is_realtime(t) && budget_enforced(t) && budget_exhausted(t)) {
                 if (!is_np(t)) {
                         /* np tasks will be preempted when they become
                          * preemptable again
@@ -379,7 +379,9 @@ static struct task_struct* cedf_schedule(struct task_struct * prev)
         /* (0) Determine state */
         exists      = entry->scheduled != NULL;
         blocks      = exists && !is_running(entry->scheduled);
-        out_of_time = exists && budget_exhausted(entry->scheduled);
+        out_of_time = exists &&
+                                  budget_enforced(entry->scheduled) &&
+                                  budget_exhausted(entry->scheduled);
         np          = exists && is_np(entry->scheduled);
         sleep       = exists && get_rt_flags(entry->scheduled) == RT_F_SLEEP;
         preempt     = entry->scheduled != entry->linked;
diff --git a/litmus/sched_gsn_edf.c b/litmus/sched_gsn_edf.c
index 7424c183d8b2..c0c63eba70ce 100644
--- a/litmus/sched_gsn_edf.c
+++ b/litmus/sched_gsn_edf.c
@@ -336,7 +336,7 @@ static noinline void job_completion(struct task_struct *t, int forced)
  */
 static void gsnedf_tick(struct task_struct* t)
 {
-        if (is_realtime(t) && budget_exhausted(t)) {
+        if (is_realtime(t) && budget_enforced(t) && budget_exhausted(t)) {
                 if (!is_np(t)) {
                         /* np tasks will be preempted when they become
                          * preemptable again
@@ -399,7 +399,9 @@ static struct task_struct* gsnedf_schedule(struct task_struct * prev)
         /* (0) Determine state */
         exists      = entry->scheduled != NULL;
         blocks      = exists && !is_running(entry->scheduled);
-        out_of_time = exists && budget_exhausted(entry->scheduled);
+        out_of_time = exists &&
+                                  budget_enforced(entry->scheduled) &&
+                                  budget_exhausted(entry->scheduled);
         np          = exists && is_np(entry->scheduled);
         sleep       = exists && get_rt_flags(entry->scheduled) == RT_F_SLEEP;
         preempt     = entry->scheduled != entry->linked;
diff --git a/litmus/sched_psn_edf.c b/litmus/sched_psn_edf.c
index 7a548bf5162e..e50b27391d21 100644
--- a/litmus/sched_psn_edf.c
+++ b/litmus/sched_psn_edf.c
@@ -107,7 +107,7 @@ static void psnedf_tick(struct task_struct *t)
          */
         BUG_ON(is_realtime(t) && t != pedf->scheduled);
 
-        if (is_realtime(t) && budget_exhausted(t)) {
+        if (is_realtime(t) && budget_enforced(t) && budget_exhausted(t)) {
                 if (!is_np(t)) {
                         set_tsk_need_resched(t);
                         TRACE("psnedf_scheduler_tick: "
@@ -143,7 +143,9 @@ static struct task_struct* psnedf_schedule(struct task_struct * prev)
         /* (0) Determine state */
         exists      = pedf->scheduled != NULL;
         blocks      = exists && !is_running(pedf->scheduled);
-        out_of_time = exists && budget_exhausted(pedf->scheduled);
+        out_of_time = exists &&
+                                  budget_enforced(pedf->scheduled) &&
+                                  budget_exhausted(pedf->scheduled);
         np          = exists && is_np(pedf->scheduled);
         sleep       = exists && get_rt_flags(pedf->scheduled) == RT_F_SLEEP;
         preempt     = edf_preemption_needed(edf, prev);