From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Kirsher Subject: [net-next 14/15] net: e1000: support txtd update delay via xmit_more Date: Thu, 22 Jan 2015 18:37:10 -0800 Message-ID: <1421980631-1955-15-git-send-email-jeffrey.t.kirsher@intel.com> References: <1421980631-1955-1-git-send-email-jeffrey.t.kirsher@intel.com> Cc: Florian Westphal , netdev@vger.kernel.org, nhorman@redhat.com, sassmann@redhat.com, jogreene@redhat.com, Jeff Kirsher To: davem@davemloft.net Return-path: Received: from mga14.intel.com ([192.55.52.115]:16348 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753484AbbAWChY (ORCPT ); Thu, 22 Jan 2015 21:37:24 -0500 In-Reply-To: <1421980631-1955-1-git-send-email-jeffrey.t.kirsher@intel.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Florian Westphal Don't update Tx tail descriptor if we queue hasn't been stopped and we know at least one more skb will be sent right away. Signed-off-by: Florian Westphal Tested-by: Aaron Brown Signed-off-by: Jeff Kirsher --- drivers/net/ethernet/intel/e1000/e1000_main.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/drivers/net/ethernet/intel/e1000/e1000_main.c b/drivers/net/ethernet/intel/e1000/e1000_main.c index 9242982..7f997d3 100644 --- a/drivers/net/ethernet/intel/e1000/e1000_main.c +++ b/drivers/net/ethernet/intel/e1000/e1000_main.c @@ -2977,7 +2977,6 @@ static void e1000_tx_queue(struct e1000_adapter *adapter, struct e1000_tx_ring *tx_ring, int tx_flags, int count) { - struct e1000_hw *hw = &adapter->hw; struct e1000_tx_desc *tx_desc = NULL; struct e1000_tx_buffer *buffer_info; u32 txd_upper = 0, txd_lower = E1000_TXD_CMD_IFCS; @@ -3031,11 +3030,6 @@ static void e1000_tx_queue(struct e1000_adapter *adapter, wmb(); tx_ring->next_to_use = i; - writel(i, hw->hw_addr + tx_ring->tdt); - /* we need this if more than one processor can write to our tail - * at a time, it synchronizes IO on IA64/Altix systems - */ - mmiowb(); } /* 82547 workaround to avoid controller hang in half-duplex environment. @@ -3264,6 +3258,15 @@ static netdev_tx_t e1000_xmit_frame(struct sk_buff *skb, /* Make sure there is space in the ring for the next send. */ e1000_maybe_stop_tx(netdev, tx_ring, MAX_SKB_FRAGS + 2); + if (!skb->xmit_more || + netif_xmit_stopped(netdev_get_tx_queue(netdev, 0))) { + writel(tx_ring->next_to_use, hw->hw_addr + tx_ring->tdt); + /* we need this if more than one processor can write to + * our tail at a time, it synchronizes IO on IA64/Altix + * systems + */ + mmiowb(); + } } else { dev_kfree_skb_any(skb); tx_ring->buffer_info[first].time_stamp = 0; -- 1.9.3