Infrastructure for Litmus signals.prop/litmus-signals

Added signals to Litmus. Specifcally, SIG_BUDGET signals
are delivered (when requested by real-time tasks) when
a budget is exceeded.

Note: pfair not currently supported (but it probably could be).

1 files changed, 31 insertions, 16 deletions

diff --git a/litmus/sched_cedf.c b/litmus/sched_cedf.c
index b0c16e34d2c5..208f067934fc 100644
--- a/litmus/sched_cedf.c
+++ b/litmus/sched_cedf.c
@@ -371,21 +371,29 @@ static noinline void job_completion(struct task_struct *t, int forced)
  */
 static void cedf_tick(struct task_struct* 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
-                         */
-                        litmus_reschedule_local();
-                        set_will_schedule();
-                        TRACE("cedf_scheduler_tick: "
-                              "%d is preemptable "
-                              " => FORCE_RESCHED\n", t->pid);
-                } else if (is_user_np(t)) {
-                        TRACE("cedf_scheduler_tick: "
-                              "%d is non-preemptable, "
-                              "preemption delayed.\n", t->pid);
-                        request_exit_np(t);
+        if (is_realtime(t) && budget_exhausted(t))
+        {
+                if (budget_signalled(t) && !sigbudget_sent(t)) {
+                        /* signal exhaustion */
+                        send_sigbudget(t);
+                }
+
+                if (budget_enforced(t)) {
+                        if (!is_np(t)) {
+                                /* np tasks will be preempted when they become
+                                 * preemptable again
+                                 */
+                                litmus_reschedule_local();
+                                set_will_schedule();
+                                TRACE("cedf_scheduler_tick: "
+                                          "%d is preemptable "
+                                          " => FORCE_RESCHED\n", t->pid);
+                        } else if (is_user_np(t)) {
+                                TRACE("cedf_scheduler_tick: "
+                                          "%d is non-preemptable, "
+                                          "preemption delayed.\n", t->pid);
+                                request_exit_np(t);
+                        }
                 }
         }
 }
@@ -415,7 +423,7 @@ static struct task_struct* cedf_schedule(struct task_struct * prev)
 {
         cpu_entry_t* entry = &__get_cpu_var(cedf_cpu_entries);
         cedf_domain_t *cluster = entry->cluster;
-        int out_of_time, sleep, preempt, np, exists, blocks;
+        int out_of_time, signal_budget, sleep, preempt, np, exists, blocks;
         struct task_struct* next = NULL;
 
 #ifdef CONFIG_RELEASE_MASTER
@@ -442,6 +450,10 @@ static struct task_struct* cedf_schedule(struct task_struct * prev)
         out_of_time = exists &&
                                   budget_enforced(entry->scheduled) &&
                                   budget_exhausted(entry->scheduled);
+        signal_budget = exists &&
+                                        budget_signalled(entry->scheduled) &&
+                                        budget_exhausted(entry->scheduled) &&
+                                        !sigbudget_sent(entry->scheduled);
         np          = exists && is_np(entry->scheduled);
         sleep       = exists && get_rt_flags(entry->scheduled) == RT_F_SLEEP;
         preempt     = entry->scheduled != entry->linked;
@@ -460,6 +472,9 @@ static struct task_struct* cedf_schedule(struct task_struct * prev)
                 TRACE_TASK(prev, "will be preempted by %s/%d\n",
                            entry->linked->comm, entry->linked->pid);
 
+        /* Send the signal that the budget has been exhausted */
+        if (signal_budget)
+                send_sigbudget(entry->scheduled);
 
         /* If a task blocks we have no choice but to reschedule.
          */