From d9df2d0a3a5bbd40771568c659d60c19e197af25 Mon Sep 17 00:00:00 2001 From: Brian Norris Date: Fri, 8 Mar 2013 15:52:26 -0800 Subject: [PATCH] ms-queue: finally, the correct (?) memory orderings With much discussion over the intent of the algorithm and the accuracy of these orderings, we have an accurate representation of the M&S Queue. --- ms-queue/my_queue.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/ms-queue/my_queue.c b/ms-queue/my_queue.c index 492c862..18ce29f 100644 --- a/ms-queue/my_queue.c +++ b/ms-queue/my_queue.c @@ -94,15 +94,15 @@ void enqueue(queue_t *q, unsigned int val) if (get_ptr(next) == 0) { // == NULL pointer value = MAKE_POINTER(node, get_count(next) + 1); success = atomic_compare_exchange_strong_explicit(&q->nodes[get_ptr(tail)].next, - &next, value, memory_order_acq_rel, memory_order_acq_rel); + &next, value, release, release); } if (!success) { - unsigned int ptr = get_ptr(atomic_load_explicit(&q->nodes[get_ptr(tail)].next, memory_order_seq_cst)); + unsigned int ptr = get_ptr(atomic_load_explicit(&q->nodes[get_ptr(tail)].next, acquire)); pointer value = MAKE_POINTER(ptr, get_count(tail) + 1); atomic_compare_exchange_strong_explicit(&q->tail, &tail, value, - memory_order_acq_rel, memory_order_acq_rel); + release, release); thrd_yield(); } } @@ -110,7 +110,7 @@ void enqueue(queue_t *q, unsigned int val) atomic_compare_exchange_strong_explicit(&q->tail, &tail, MAKE_POINTER(node, get_count(tail) + 1), - memory_order_acq_rel, memory_order_acq_rel); + release, release); } unsigned int dequeue(queue_t *q) @@ -123,7 +123,7 @@ unsigned int dequeue(queue_t *q) while (!success) { head = atomic_load_explicit(&q->head, acquire); - tail = atomic_load_explicit(&q->tail, acquire); + tail = atomic_load_explicit(&q->tail, relaxed); next = atomic_load_explicit(&q->nodes[get_ptr(head)].next, acquire); if (atomic_load_explicit(&q->head, relaxed) == head) { if (get_ptr(head) == get_ptr(tail)) { @@ -133,14 +133,14 @@ unsigned int dequeue(queue_t *q) atomic_compare_exchange_strong_explicit(&q->tail, &tail, MAKE_POINTER(get_ptr(next), get_count(tail) + 1), - memory_order_acq_rel, memory_order_acq_rel); + release, release); thrd_yield(); } else { value = load_32(&q->nodes[get_ptr(next)].value); success = atomic_compare_exchange_strong_explicit(&q->head, &head, MAKE_POINTER(get_ptr(next), get_count(head) + 1), - memory_order_acq_rel, memory_order_acq_rel); + release, release); if (!success) thrd_yield(); } -- 2.34.1