From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sowmini Varadhan Subject: [PATCH net-next 1/3] sunvnet: Do not ask for an ACK for every dring transmit Date: Tue, 12 Aug 2014 10:27:24 -0400 Message-ID: <20140812142724.GH2404@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org To: sowmini.varadhan@oracle.com, davem@davemloft.net, raghuram.kothakota@oracle.com Return-path: Received: from aserp1040.oracle.com ([141.146.126.69]:21094 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752393AbaHLO1a (ORCPT ); Tue, 12 Aug 2014 10:27:30 -0400 Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-ID: No need to ask for an ack with every vnet_start_xmit()- the single ACK with DRING_STOPPED is sufficient for the protocol, and we free the sk_buff in vnet_start_xmit itself, so we dont need an ACK back. Signed-off-by: Sowmini Varadhan Acked-by: Raghuram Kothakota --- drivers/net/ethernet/sun/sunvnet.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/sun/sunvnet.c b/drivers/net/ethernet/sun/sunvnet.c index d813bfb..b489dd0 100644 --- a/drivers/net/ethernet/sun/sunvnet.c +++ b/drivers/net/ethernet/sun/sunvnet.c @@ -691,7 +691,15 @@ static int vnet_start_xmit(struct sk_buff *skb, struct net_device *dev) memset(tx_buf+VNET_PACKET_SKIP+skb->len, 0, len - skb->len); } - d->hdr.ack = VIO_ACK_ENABLE; + /* We don't rely on the ACKs to free the skb in vnet_start_xmit(), + * thus it is safe to not set VIO_ACK_ENABLE for each transmission: + * the protocol itself does not require it as long as the peer + * sends a VIO_SUBTYPE_ACK for VIO_DRING_STOPPED. + * + * An ACK for every packet in the ring is expensive as the + * sending of LDC messages is slow and affects performance. + */ + d->hdr.ack = VIO_ACK_DISABLE; d->size = len; d->ncookies = port->tx_bufs[dr->prod].ncookies; for (i = 0; i < d->ncookies; i++) -- 1.8.4.2