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, 28 insertions, 12 deletions

diff --git a/litmus/sched_pfp.c b/litmus/sched_pfp.c
index 62be699629b1..6129eb94d3ea 100644
--- a/litmus/sched_pfp.c
+++ b/litmus/sched_pfp.c
@@ -135,17 +135,25 @@ static void pfp_tick(struct task_struct *t)
          */
         BUG_ON(is_realtime(t) && t != pfp->scheduled);
 
-        if (is_realtime(t) && budget_enforced(t) && budget_exhausted(t)) {
-                if (!is_np(t)) {
-                        litmus_reschedule_local();
-                        TRACE("pfp_scheduler_tick: "
-                              "%d is preemptable "
-                              " => FORCE_RESCHED\n", t->pid);
-                } else if (is_user_np(t)) {
-                        TRACE("pfp_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)) {
+                                litmus_reschedule_local();
+                                TRACE("pfp_scheduler_tick: "
+                                          "%d is preemptable "
+                                          " => FORCE_RESCHED\n", t->pid);
+                        } else if (is_user_np(t)) {
+                                TRACE("pfp_scheduler_tick: "
+                                          "%d is non-preemptable, "
+                                          "preemption delayed.\n", t->pid);
+                                request_exit_np(t);
+                        }
                 }
         }
 }
@@ -155,7 +163,7 @@ static struct task_struct* pfp_schedule(struct task_struct * prev)
         pfp_domain_t*   pfp = local_pfp;
         struct task_struct*     next;
 
-        int out_of_time, sleep, preempt, np, exists, blocks, resched, migrate;
+        int out_of_time, signal_budget, sleep, preempt, np, exists, blocks, resched, migrate;
 
         raw_spin_lock(&pfp->slock);
 
@@ -172,6 +180,10 @@ static struct task_struct* pfp_schedule(struct task_struct * prev)
         out_of_time = exists &&
                                   budget_enforced(pfp->scheduled) &&
                                   budget_exhausted(pfp->scheduled);
+        signal_budget = exists &&
+                                        budget_signalled(pfp->scheduled) &&
+                                        budget_exhausted(pfp->scheduled) &&
+                                        !sigbudget_sent(pfp->scheduled);
         np          = exists && is_np(pfp->scheduled);
         sleep       = exists && get_rt_flags(pfp->scheduled) == RT_F_SLEEP;
         migrate     = exists && get_partition(pfp->scheduled) != pfp->cpu;
@@ -183,6 +195,10 @@ static struct task_struct* pfp_schedule(struct task_struct * prev)
          */
         resched = preempt;
 
+        /* Send the signal that the budget has been exhausted */
+        if (signal_budget)
+                send_sigbudget(pfp->scheduled);
+
         /* If a task blocks we have no choice but to reschedule.
          */
         if (blocks)