Donees cannot be amongst the top-m requests.

1 files changed, 13 insertions, 5 deletions

diff --git a/litmus/ikglp_lock.c b/litmus/ikglp_lock.c
index 1ce6572eddcb..1a5d674b26a5 100644
--- a/litmus/ikglp_lock.c
+++ b/litmus/ikglp_lock.c
@@ -1957,8 +1957,11 @@ static ikglp_donee_heap_node_t* pick_donee(struct ikglp_affinity* aff,
         struct ikglp_semaphore *sem = ikglp_from_lock(aff->obs.lock);
         struct task_struct *donee;
         ikglp_donee_heap_node_t *donee_node;
+        struct task_struct *mth_highest = ikglp_mth_highest(sem);
         
-        if(fq->owner && fq->donee_heap_node.donor_info != NULL) {
+        if(fq->owner &&
+           fq->donee_heap_node.donor_info != NULL &&
+           litmus->__compare(mth_highest, BASE, fq->owner, BASE)) {
                 donee = fq->owner;
                 donee_node = &(fq->donee_heap_node);
                 *dist_from_head = 0;
@@ -1979,8 +1982,9 @@ static ikglp_donee_heap_node_t* pick_donee(struct ikglp_affinity* aff,
                 // the donee will be closer to obtaining a resource.
                 list_for_each(pos, &fq->wait.task_list) {
                         wait_queue_t *fq_wait = list_entry(pos, wait_queue_t, task_list);
-                        if(!has_donor(fq_wait)) {
-                                ikglp_wait_state_t *wait = container_of(fq_wait, ikglp_wait_state_t, fq_node);
+                        ikglp_wait_state_t *wait = container_of(fq_wait, ikglp_wait_state_t, fq_node);
+                        if(!has_donor(fq_wait) &&
+                           litmus->__compare(mth_highest, BASE, wait->task, BASE)) {
                                 donee = (struct task_struct*) fq_wait->private;
                                 donee_node = &wait->donee_heap_node;
                                 
@@ -2019,8 +2023,9 @@ ikglp_donee_heap_node_t* gpu_ikglp_advise_donee_selection(
                                                                                         struct task_struct* donor)
 {
         // Huristic strategy: Find the highest-priority donee that is waiting on
-        // a queue closest to our affinity.  The donee CANNOT already have a donor
-        // (exception: donee is the lowest-prio task in the donee heap).
+        // a queue closest to our affinity.  (1) The donee CANNOT already have a
+        // donor (exception: donee is the lowest-prio task in the donee heap).
+        // (2) Requests in 'top_m' heap are ineligible.
         //
         // Further strategy: amongst elible donees waiting for the same GPU, pick
         // the one closest to the head of the FIFO queue (including owners).
@@ -2058,6 +2063,9 @@ ikglp_donee_heap_node_t* gpu_ikglp_advise_donee_selection(
         donee_node = NULL;
         distance = MIG_NONE;
         
+        // TODO: The below search logic may work well for locating nodes to steal
+        // when an FQ goes idle.  Validate this code and apply it to stealing.
+        
         // begin search with affinity GPU.
         start = gpu_to_base_replica(aff, tsk_rt(donor)->last_gpu);
         i = start;