net/virtio: add Rx free threshold setting

Introduce free threshold setting in Rx queue, its default value is 32.
Limit the threshold size to multiple of four as only vectorized packed
Rx function will utilize it. Virtio driver will rearm Rx queue when
more than rx_free_thresh descs were dequeued.

Signed-off-by: Marvin Liu <yong.liu@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
index 060410577af424def4784a536fc39f43de4d981d..94ba7a3ecb507f01f8677d307977db12b0c705bb 100644 (file)
--- a/drivers/net/virtio/virtio_rxtx.c
+++ b/drivers/net/virtio/virtio_rxtx.c
@@ -936,6 +936,7 @@ virtio_dev_rx_queue_setup(struct rte_eth_dev *dev,
        struct virtio_hw *hw = dev->data->dev_private;
        struct virtqueue *vq = hw->vqs[vtpci_queue_idx];
        struct virtnet_rx *rxvq;
+       uint16_t rx_free_thresh;
 
        PMD_INIT_FUNC_TRACE();
 
@@ -944,6 +945,28 @@ virtio_dev_rx_queue_setup(struct rte_eth_dev *dev,
                return -EINVAL;
        }
 
+       rx_free_thresh = rx_conf->rx_free_thresh;
+       if (rx_free_thresh == 0)
+               rx_free_thresh =
+                       RTE_MIN(vq->vq_nentries / 4, DEFAULT_RX_FREE_THRESH);
+
+       if (rx_free_thresh & 0x3) {
+               RTE_LOG(ERR, PMD, "rx_free_thresh must be multiples of four."
+                       " (rx_free_thresh=%u port=%u queue=%u)\n",
+                       rx_free_thresh, dev->data->port_id, queue_idx);
+               return -EINVAL;
+       }
+
+       if (rx_free_thresh >= vq->vq_nentries) {
+               RTE_LOG(ERR, PMD, "rx_free_thresh must be less than the "
+                       "number of RX entries (%u)."
+                       " (rx_free_thresh=%u port=%u queue=%u)\n",
+                       vq->vq_nentries,
+                       rx_free_thresh, dev->data->port_id, queue_idx);
+               return -EINVAL;
+       }
+       vq->vq_free_thresh = rx_free_thresh;
+
        if (nb_desc == 0 || nb_desc > vq->vq_nentries)
                nb_desc = vq->vq_nentries;
        vq->vq_free_cnt = RTE_MIN(vq->vq_free_cnt, nb_desc);

diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
index e3d38b5a671bbdc931f80ab3e1a417ea0c46298f..011a67af21090a64aa8cabf8e9987c89ae2e07cb 100644 (file)
--- a/drivers/net/virtio/virtqueue.h
+++ b/drivers/net/virtio/virtqueue.h
@@ -18,6 +18,8 @@
 
 struct rte_mbuf;
 
+#define DEFAULT_RX_FREE_THRESH 32
+
 /*
  * Per virtio_ring.h in Linux.
  *     For virtio_pci on SMP, we don't need to order with respect to MMIO