load-acquire memory order has a barrier. Loading it inside
the loop will result in a barrier in every iteration. Hence,
load the variable once outside the loop.
Signed-off-by: Honnappa Nagarahalli <honnappa.nagaraha...@arm.com>
Reviewed-by: Phil Yang <phil.y...@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.w...@arm.com>
---
drivers/net/memif/rte_eth_memif.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/net/memif/rte_eth_memif.c
b/drivers/net/memif/rte_eth_memif.c
index 704350022..c73cde8fd 100644
--- a/drivers/net/memif/rte_eth_memif.c
+++ b/drivers/net/memif/rte_eth_memif.c
@@ -249,16 +249,17 @@ memif_get_buffer(struct pmd_process_private
*proc_private, memif_desc_t *d)
static void
memif_free_stored_mbufs(struct pmd_process_private *proc_private, struct
memif_queue *mq)
{
+ uint16_t cur_tail;
uint16_t mask = (1 << mq->log2_ring_size) - 1;
memif_ring_t *ring = memif_get_ring_from_queue(proc_private, mq);
/* FIXME: improve performance */
/* The ring->tail acts as a guard variable between Tx and Rx
* threads, so using load-acquire pairs with store-release
- * to synchronize it between threads.
+ * in function eth_memif_rx for S2M queues.
*/
- while (mq->last_tail != __atomic_load_n(&ring->tail,
- __ATOMIC_ACQUIRE)) {
+ cur_tail = __atomic_load_n(&ring->tail, __ATOMIC_ACQUIRE);
+ while (mq->last_tail != cur_tail) {
RTE_MBUF_PREFETCH_TO_FREE(mq->buffers[(mq->last_tail + 1) &
mask]);
/* Decrement refcnt and free mbuf. (current segment) */
rte_mbuf_refcnt_update(mq->buffers[mq->last_tail & mask], -1);
--
2.17.1
