@@ -568,12 +568,10 @@ eth_memif_tx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
ring_size = 1 << mq->log2_ring_size;
mask = ring_size - 1;
- n_free = __atomic_load_n(&ring->tail, __ATOMIC_ACQUIRE) - mq->last_tail;
- mq->last_tail += n_free;
-
if (type == MEMIF_RING_S2M) {
slot = __atomic_load_n(&ring->head, __ATOMIC_ACQUIRE);
- n_free = ring_size - slot + mq->last_tail;
+ n_free = ring_size - slot +
+ __atomic_load_n(&ring->tail, __ATOMIC_ACQUIRE);
} else {
slot = __atomic_load_n(&ring->tail, __ATOMIC_ACQUIRE);
n_free = __atomic_load_n(&ring->head, __ATOMIC_ACQUIRE) - slot;
In the case of S2M queues, the receiver synchronizes with the sender (i.e. informs of the packets it has received) using ring->tail. Hence, the sender does not need to update last_tail. In the case of M2S queues, the receiver uses last_tail to keep track of the descriptors it has received. The sender is not required to update the last_tail. Updating the last_tail makes it a shared variable between the transmitter and receiver affecting the performance. Fixes: 09c7e63a71f9 ("net/memif: introduce memory interface PMD") Cc: jgrajcia@cisco.com Cc: stable@dpdk.org Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com> Reviewed-by: Phil Yang <phil.yang@arm.com> --- drivers/net/memif/rte_eth_memif.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) -- 2.17.1