Like most dirvers, make the fast path of virtio_xmit_cleanup() behave as
described by the comments of rte_eth_txconf::tx_free_thresh ([0]):
Start freeing Tx buffers if there are
less free descriptors than this value.
The rationale behind this change is that:
* vq->vq_nentries is set during device probe with the queue size specified
by vhost backend, this value does not reflect the real nb_tx_desc
* the real available tx desc is set to vq->vq_free_cnt via the nb_tx_desc
param of rte_eth_tx_queue_setup() API
* so `nb_used > vq->vq_nentries - vq->vq_free_thresh` could never be true
if say nb_tx_desc=2048, vq->vq_nentries=4096, vq->vq_free_thresh=32,
see bug report 1716 ([1]) for details.
Bugzilla ID: 1716
[0]: https://github.com/DPDK/dpdk/commit/72514b5d5543
[1]: https://bugs.dpdk.org/show_bug.cgi?id=1716
Signed-off-by: Baoyuan Li <updo...@sina.com>
Signed-off-by: Hengqi Chen <hengqi.c...@gmail.com>
---
drivers/net/virtio/virtio_rxtx.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
index edecd2011f..ab97f03d7d 100644
--- a/drivers/net/virtio/virtio_rxtx.c
+++ b/drivers/net/virtio/virtio_rxtx.c
@@ -1873,7 +1873,7 @@ virtio_xmit_pkts(void *tx_queue, struct rte_mbuf
**tx_pkts, uint16_t nb_pkts)
nb_used = virtqueue_nused(vq);
- if (likely(nb_used > vq->vq_nentries - vq->vq_free_thresh))
+ if (likely(vq->vq_free_cnt < vq->vq_free_thresh))
virtio_xmit_cleanup(vq, nb_used);
for (nb_tx = 0; nb_tx < nb_pkts; nb_tx++) {
--
2.43.5
