The 82576 has known issues which require the write threshold to be set to 1. See: http://download.intel.com/design/network/specupdt/82576_SPECUPDATE.pdf If not then single packets will hang in transmit ring until more arrive. Simple tests like ping will fail. Signed-off-by: Stephen Hemminger --- lib/librte_pmd_e1000/em_rxtx.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/lib/librte_pmd_igb/e1000_rxtx.c 2013-03-28 08:50:50.238413818 -0700 +++ b/lib/librte_pmd_igb/e1000_rxtx.c 2013-05-29 08:49:02.369979711 -0700 @@ -1240,6 +1240,8 @@ eth_igb_tx_queue_setup(struct rte_eth_de txq->pthresh = tx_conf->tx_thresh.pthresh; txq->hthresh = tx_conf->tx_thresh.hthresh; txq->wthresh = tx_conf->tx_thresh.wthresh; + if (txq->wthresh > 0 && hw->mac.type == e1000_82576) + txq->wthresh = 1; txq->queue_id = queue_idx; txq->port_id = dev->data->port_id; @@ -1384,6 +1386,9 @@ eth_igb_rx_queue_setup(struct rte_eth_de rxq->pthresh = rx_conf->rx_thresh.pthresh; rxq->hthresh = rx_conf->rx_thresh.hthresh; rxq->wthresh = rx_conf->rx_thresh.wthresh; + if (rxq->wthresh > 0 && hw->mac.type == e1000_82576) + rxq->wthresh = 1; + rxq->rx_free_thresh = rx_conf->rx_free_thresh; rxq->queue_id = queue_idx; rxq->port_id = dev->data->port_id;