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 <kys@xxxxxxxxxxxxx>
---
v2: Fixed up indentation based on feedback from David Miller.
v3,v4: If the queue could be stopped, deal with that condition: Eric Dumazet <eric.dumazet@xxxxxxxxx>
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
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