Index: openmp/trunk/runtime/src/kmp_tasking.c =================================================================== --- openmp/trunk/runtime/src/kmp_tasking.c +++ openmp/trunk/runtime/src/kmp_tasking.c @@ -1782,18 +1782,10 @@ KMP_DEBUG_ASSERT( victim_td -> td.td_deque != NULL ); - if ( !is_constrained ) { - taskdata = victim_td -> td.td_deque[ victim_td -> td.td_deque_head ]; - KMP_ASSERT(taskdata); - // Bump head pointer and Wrap. - victim_td -> td.td_deque_head = ( victim_td -> td.td_deque_head + 1 ) & TASK_DEQUE_MASK(victim_td->td); - } else { - // While we have postponed tasks let's steal from tail of the deque (smaller tasks) - kmp_int32 tail = ( victim_td -> td.td_deque_tail - 1 ) & TASK_DEQUE_MASK(victim_td->td); // Wrap index. - taskdata = victim_td -> td.td_deque[ tail ]; - KMP_ASSERT(taskdata); + taskdata = victim_td->td.td_deque[victim_td->td.td_deque_head]; + if ( is_constrained ) { // we need to check if the candidate obeys task scheduling constraint: - // only child of current task can be scheduled + // only descendant of current task can be scheduled kmp_taskdata_t * current = __kmp_threads[ gtid ]->th.th_current_task; kmp_int32 level = current->td_level; kmp_taskdata_t * parent = taskdata->td_parent; @@ -1802,7 +1794,9 @@ KMP_DEBUG_ASSERT(parent != NULL); } if ( parent != current ) { - // If the tail task is not a descendant of the current task then do not steal it. + // If the head task is not a descendant of the current task then do not + // steal it. No other task in victim's deque can be a descendant of the + // current task. __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 " "ntasks=%d head=%u tail=%u\n", @@ -1811,8 +1805,9 @@ victim_td->td.td_deque_head, victim_td->td.td_deque_tail) ); return NULL; } - victim_td -> td.td_deque_tail = tail; } + // Bump head pointer and Wrap. + victim_td->td.td_deque_head = (victim_td->td.td_deque_head + 1) & TASK_DEQUE_MASK(victim_td->td); if (*thread_finished) { // We need to un-mark this victim as a finished victim. This must be done before // releasing the lock, or else other threads (starting with the master victim)