Exclude untied tasks from task stealing constraint

jpeyton52 · jpeyton52 · commit 8cb45c838f99 · 2016-06-13T17:51:59.000Z
If either current_task or new_task is untied then skip task scheduling constraint checks, because untied tasks are not affected by the task scheduling constraints. Differential Revision: http://reviews.llvm.org/D21196 llvm-svn: 272570
diff --git a/openmp/runtime/src/kmp_tasking.c b/openmp/runtime/src/kmp_tasking.c
@@ -1644,7 +1644,7 @@ __kmp_remove_my_task( kmp_info_t * thread, kmp_int32 gtid, kmp_task_team_t *task
     tail = ( thread_data -> td.td_deque_tail - 1 ) & TASK_DEQUE_MASK(thread_data->td);  // Wrap index.
     taskdata = thread_data -> td.td_deque[ tail ];
 
-    if (is_constrained) {
+    if (is_constrained && (taskdata->td_flags.tiedness == TASK_TIED)) {
         // we need to check if the candidate obeys task scheduling constraint:
         // only child of current task can be scheduled
         kmp_taskdata_t * current = thread->th.th_current_task;
@@ -1751,7 +1751,7 @@ __kmp_steal_task( kmp_info_t *victim, kmp_int32 gtid, kmp_task_team_t *task_team
             parent = parent->td_parent;  // check generation up to the level of the current task
             KMP_DEBUG_ASSERT(parent != NULL);
         }
-        if ( parent != current ) {
+        if ( parent != current && (taskdata->td_flags.tiedness == TASK_TIED) ) { // untied is always allowed to be stolen
             // If the tail task is not a child, then no other childs can appear in the deque (?).
             __kmp_release_bootstrap_lock( & victim_td -> td.td_deque_lock );
             KA_TRACE(10, ("__kmp_steal_task(exit #2): T#%d could not steal from T#%d: task_team=%p "
