EDF-WM: trace reasons why a task was rejected

Makes debugging easier.

1 files changed, 27 insertions, 8 deletions

diff --git a/litmus/sched_edf_wm.c b/litmus/sched_edf_wm.c
index ba69969b9a1c..64a096bd02ca 100644
--- a/litmus/sched_edf_wm.c
+++ b/litmus/sched_edf_wm.c
@@ -521,46 +521,65 @@ static long wm_check_params(struct task_struct *t)
                 return 0;
 
         /* (1) Either not sliced, or more than 1 slice. */
-        if (wm->count == 1 || wm->count > MAX_EDF_WM_SLICES)
+        if (wm->count == 1 || wm->count > MAX_EDF_WM_SLICES) {
+                TRACE_TASK(t, "bad number of slices (%u) \n",
+                           wm->count);
                 return -EINVAL;
+        }
 
         /* (2) The partition has to agree with the first slice. */
-        if (get_partition(t) != wm->slices[0].cpu)
+        if (get_partition(t) != wm->slices[0].cpu) {
+                TRACE_TASK(t, "partition and first slice CPU differ\n");
                 return -EINVAL;
+        }
 
         /* (3) The total budget must agree. */
         for (i = 0, tmp = 0; i < wm->count; i++)
                 tmp += wm->slices[i].budget;
-        if (get_exec_cost(t) != tmp)
+        if (get_exec_cost(t) != tmp) {
+                TRACE_TASK(t, "total budget and sum of slice budgets differ\n");
                 return -EINVAL;
+        }
 
         /* (4) The release of each slice must not precede the previous
          *     deadline. */
         for (i = 0; i < wm->count - 1; i++)
-                if (wm->slices[i].deadline > wm->slices[i + 1].offset)
+                if (wm->slices[i].deadline > wm->slices[i + 1].offset) {
+                        TRACE_TASK(t, "slice %d overlaps with slice %d\n",
+                                   i, i + 1);
                         return -EINVAL;
+                }
 
         /* (5) The budget of each slice must fit within [offset, deadline] */
         for (i = 0; i < wm->count; i++)
                 if (lt_before(wm->slices[i].deadline, wm->slices[i].offset) ||
                     wm->slices[i].deadline - wm->slices[i].offset <
-                    wm->slices[i].budget)
+                    wm->slices[i].budget) {
+                        TRACE_TASK(t, "slice %d is overloaded\n", i);
                         return -EINVAL;
+                }
 
         /* (6) The budget of each slice must exceed the minimum budget size. */
         for (i = 0; i < wm->count; i++)
-                if (wm->slices[i].budget < MIN_EDF_WM_SLICE_SIZE)
+                if (wm->slices[i].budget < MIN_EDF_WM_SLICE_SIZE) {
+                        TRACE_TASK(t, "slice %d is too short\n", i);
                         return -EINVAL;
+                }
 
         /* (7) The CPU of each slice must be different from the previous CPU. */
         for (i = 0; i < wm->count - 1; i++)
-                if (wm->slices[i].cpu == wm->slices[i + 1].cpu)
+                if (wm->slices[i].cpu == wm->slices[i + 1].cpu) {
+                        TRACE_TASK(t, "slice %d does not migrate\n", i);
                         return -EINVAL;
+                }
 
         /* (8) The CPU of each slice must be online. */
         for (i = 0; i < wm->count; i++)
-                if (!cpu_online(wm->slices[i].cpu))
+                if (!cpu_online(wm->slices[i].cpu)) {
+                        TRACE_TASK(t, "slice %d is allocated on offline CPU\n",
+                                   i);
                         return -EINVAL;
+                }
 
         return 0;
 }