Subject: Re: [PATCH 2/2 net-next] hyperv: Support batched notification

From: Jason Wang <[email-masked]>
Date: Wed, 11 Mar 2015 11:34:27 +0800

On Wed, Mar 11, 2015 at 2:50 AM, K. Y. Srinivasan <[email-masked]> 
wrote:
> Optimize notifying the host by deferring notification until there
> are no more packets to be sent. This will help in batching the 
> requests
> on the host.
> 
> Signed-off-by: K. Y. Srinivasan <[email-masked]>
> ---
>  drivers/net/hyperv/hyperv_net.h   |    2 +-
>  drivers/net/hyperv/netvsc.c       |   14 +++++++++-----
>  drivers/net/hyperv/netvsc_drv.c   |    3 ++-
>  drivers/net/hyperv/rndis_filter.c |    2 +-
>  4 files changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/net/hyperv/hyperv_net.h 
> b/drivers/net/hyperv/hyperv_net.h
> index 4815843..3fd9896 100644
> --- a/drivers/net/hyperv/hyperv_net.h
> +++ b/drivers/net/hyperv/hyperv_net.h
> @@ -184,7 +184,7 @@ struct rndis_device {
>  int netvsc_device_add(struct hv_device *device, void 
> *additional_info);
>  int netvsc_device_remove(struct hv_device *device);
>  int netvsc_send(struct hv_device *device,
> -		struct hv_netvsc_packet *packet);
> +		struct hv_netvsc_packet *packet, bool kick_q);
>  void netvsc_linkstatus_callback(struct hv_device *device_obj,
>  				struct rndis_message *resp);
>  int netvsc_recv_callback(struct hv_device *device_obj,
> diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
> index 208eb05..9003b94 100644
> --- a/drivers/net/hyperv/netvsc.c
> +++ b/drivers/net/hyperv/netvsc.c
> @@ -707,7 +707,7 @@ static u32 netvsc_copy_to_send_buf(struct 
> netvsc_device *net_device,
>  }
>  
>  int netvsc_send(struct hv_device *device,
> -			struct hv_netvsc_packet *packet)
> +			struct hv_netvsc_packet *packet, bool kick_q)
>  {
>  	struct netvsc_device *net_device;
>  	int ret = 0;
> @@ -719,6 +719,7 @@ int netvsc_send(struct hv_device *device,
>  	u32 msg_size = 0;
>  	struct sk_buff *skb = NULL;
>  	u16 q_idx = packet->q_idx;
> +	u32 vmbus_flags = VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED;
>  
>  
>  	net_device = get_outbound_net_device(device);
> @@ -768,18 +769,21 @@ int netvsc_send(struct hv_device *device,
>  		return -ENODEV;
>  
>  	if (packet->page_buf_cnt) {
> -		ret = vmbus_sendpacket_pagebuffer(out_channel,
> +		ret = vmbus_sendpacket_pagebuffer_ctl(out_channel,
>  						  packet->page_buf,
>  						  packet->page_buf_cnt,
>  						  &sendMessage,
>  						  sizeof(struct nvsp_message),
> -						  req_id);
> +						  req_id,
> +						  vmbus_flags,
> +						  kick_q);

What if kick_q is false but ret is -EAGAIN here? Looks like in this 
case host won't get notified at all. How about checking whether txq and 
kicking if it has been stopped like what other network driver did?
> 
>  	} else {
> -		ret = vmbus_sendpacket(out_channel, &sendMessage,
> +		ret = vmbus_sendpacket_ctl(out_channel, &sendMessage,
>  				sizeof(struct nvsp_message),
>  				req_id,
>  				VM_PKT_DATA_INBAND,
> -				VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
> +				vmbus_flags,
> +				kick_q);
>  	}
>  
>  	if (ret == 0) {
> diff --git a/drivers/net/hyperv/netvsc_drv.c 
> b/drivers/net/hyperv/netvsc_drv.c
> index a06bd66..80b4b29 100644
> --- a/drivers/net/hyperv/netvsc_drv.c
> +++ b/drivers/net/hyperv/netvsc_drv.c
> @@ -384,6 +384,7 @@ static int netvsc_start_xmit(struct sk_buff *skb, 
> struct net_device *net)
>  	u32 net_trans_info;
>  	u32 hash;
>  	u32 skb_length = skb->len;
> +	bool kick_q = !skb->xmit_more;
>  
>  
>  	/* We will atmost need two pages to describe the rndis
> @@ -556,7 +557,7 @@ do_send:
>  	packet->page_buf_cnt = init_page_array(rndis_msg, rndis_msg_size,
>  					skb, &packet->page_buf[0]);
>  
> -	ret = netvsc_send(net_device_ctx->device_ctx, packet);
> +	ret = netvsc_send(net_device_ctx->device_ctx, packet, kick_q);
>  
>  drop:
>  	if (ret == 0) {
> diff --git a/drivers/net/hyperv/rndis_filter.c 
> b/drivers/net/hyperv/rndis_filter.c
> index ca81de0..05f3792 100644
> --- a/drivers/net/hyperv/rndis_filter.c
> +++ b/drivers/net/hyperv/rndis_filter.c
> @@ -238,7 +238,7 @@ static int rndis_filter_send_request(struct 
> rndis_device *dev,
>  
>  	packet->send_completion = NULL;
>  
> -	ret = netvsc_send(dev->net_dev->dev, packet);
> +	ret = netvsc_send(dev->net_dev->dev, packet, true);
>  	return ret;
>  }
>  
> -- 
> 1.7.4.1
>