1 files changed, 14 insertions, 2 deletions

diff --git a/include/litmus/gpu_affinity.h b/include/litmus/gpu_affinity.h
index c29ff3de997c..ca4d10b93203 100644
--- a/include/litmus/gpu_affinity.h
+++ b/include/litmus/gpu_affinity.h
@@ -31,9 +31,21 @@ static inline lt_t get_gpu_time(struct task_struct* t)
 
 static inline lt_t get_gpu_estimate(struct task_struct* t, gpu_migration_dist_t dist)
 {
-        lt_t val = _fp_to_integer(t->rt_param.gpu_migration_est[dist].est);
+        int i;
+        fpbuf_t temp = _fp_to_integer(t->rt_param.gpu_migration_est[dist].est);
+        lt_t val = (temp >= 0) ? temp : 0;  // never allow negative estimates...
         
-        // minimum value is 1.
+        WARN_ON(temp < 0);
+        
+        // lower-bound a distant migration to be at least equal to the level
+        // below it.
+        for(i = dist-1; (val == 0) && (i >= MIG_LOCAL); --i) {
+                val = _fp_to_integer(t->rt_param.gpu_migration_est[i].est);
+        }
+        
+        // minimum value is 1 (val is 0 if we haven't run with local affinity yet)
+        // TODO: pick a better default min-value.  1 is too small.  perhaps
+        // task execution time?
         return ((val > 0) ? val : 1);
 }