From mboxrd@z Thu Jan 1 00:00:00 1970 From: "K. Y. Srinivasan" Subject: [PATCH V4 net-next 1/1] hv_netvsc: Use the xmit_more skb flag to optimize signaling the host Date: Wed, 6 May 2015 15:29:05 -0700 Message-ID: <1430951345-7767-1-git-send-email-kys@microsoft.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: davem@davemloft.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, devel@linuxdriverproject.org, olaf@aepfle.de, apw@canonical.com, jasowang@redhat.com Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: driverdev-devel-bounces@linuxdriverproject.org Sender: "devel" List-Id: netdev.vger.kernel.org Based on the information given to this driver (via the xmit_more skb flag), we can defer signaling the host if more packets are on the way. This will help make the host more efficient since it can potentially process a larger batch of packets. Implement this optimization. Signed-off-by: K. Y. Srinivasan --- v2: Fixed up indentation based on feedback from David Miller. v3,v4: If the queue could be stopped, deal with that condition: Eric Dumazet drivers/net/hyperv/netvsc.c | 34 ++++++++++++++++++++++++---------- 1 files changed, 24 insertions(+), 10 deletions(-) diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c index ea091bc..1ab4f9e 100644 --- a/drivers/net/hyperv/netvsc.c +++ b/drivers/net/hyperv/netvsc.c @@ -743,6 +743,8 @@ static inline int netvsc_send_pkt( u64 req_id; int ret; struct hv_page_buffer *pgbuf; + u32 vmbus_flags = VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED; + u32 ring_avail = hv_ringbuf_avail_percent(&out_channel->outbound); nvmsg.hdr.msg_type = NVSP_MSG1_TYPE_SEND_RNDIS_PKT; if (packet->is_data_pkt) { @@ -769,30 +771,42 @@ static inline int netvsc_send_pkt( if (out_channel->rescind) return -ENODEV; + /* + * It is possible that once we successfully place this packet + * on the ringbuffer, we may stop the queue. In that case, we want + * to notify the host independent of the xmit_more flag. We don't + * need to be precise here; in the worst case we may signal the host + * unnecessarily. + */ + if (ring_avail < (RING_AVAIL_PERCENT_LOWATER + 1)) + packet->xmit_more = false; + if (packet->page_buf_cnt) { pgbuf = packet->cp_partial ? packet->page_buf + packet->rmsg_pgcnt : packet->page_buf; - ret = vmbus_sendpacket_pagebuffer(out_channel, - pgbuf, - packet->page_buf_cnt, - &nvmsg, - sizeof(struct nvsp_message), - req_id); + ret = vmbus_sendpacket_pagebuffer_ctl(out_channel, + pgbuf, + packet->page_buf_cnt, + &nvmsg, + sizeof(struct + nvsp_message), + req_id, + vmbus_flags, + !packet->xmit_more); } else { - ret = vmbus_sendpacket( + ret = vmbus_sendpacket_ctl( out_channel, &nvmsg, sizeof(struct nvsp_message), req_id, VM_PKT_DATA_INBAND, - VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED); + vmbus_flags, !packet->xmit_more); } if (ret == 0) { atomic_inc(&net_device->num_outstanding_sends); atomic_inc(&net_device->queue_sends[q_idx]); - if (hv_ringbuf_avail_percent(&out_channel->outbound) < - RING_AVAIL_PERCENT_LOWATER) { + if (ring_avail < RING_AVAIL_PERCENT_LOWATER) { netif_tx_stop_queue(netdev_get_tx_queue( ndev, q_idx)); -- 1.7.4.1