netdev - RE: [PATCH V3 2/2 net-next] hyperv: Support batched notification

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Date:	Thu, 19 Mar 2015 16:53:57 +0000
From:	KY Srinivasan <kys@...rosoft.com>
To:	Jason Wang <jasowang@...hat.com>
CC:	"davem@...emloft.net" <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
	"olaf@...fle.de" <olaf@...fle.de>,
	"apw@...onical.com" <apw@...onical.com>
Subject: RE: [PATCH V3 2/2 net-next] hyperv: Support batched notification



> -----Original Message-----
> From: Jason Wang [mailto:jasowang@...hat.com]
> Sent: Tuesday, March 17, 2015 8:09 PM
> To: KY Srinivasan
> Cc: davem@...emloft.net; netdev@...r.kernel.org; linux-
> kernel@...r.kernel.org; devel@...uxdriverproject.org; olaf@...fle.de;
> apw@...onical.com; KY Srinivasan
> Subject: Re: [PATCH V3 2/2 net-next] hyperv: Support batched notification
> 
> 
> 
> On Wed, Mar 18, 2015 at 12:02 AM, K. Y. Srinivasan <kys@...rosoft.com>
> 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 <kys@...rosoft.com>
> > ---
> >  drivers/net/hyperv/hyperv_net.h   |    2 +-
> >  drivers/net/hyperv/netvsc.c       |   14 +++++++++-----
> >  drivers/net/hyperv/netvsc_drv.c   |    2 +-
> >  drivers/net/hyperv/rndis_filter.c |    2 +-
> >  4 files changed, 12 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);
> >  	} 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..eae58db 100644
> > --- a/drivers/net/hyperv/netvsc_drv.c
> > +++ b/drivers/net/hyperv/netvsc_drv.c
> > @@ -556,7 +556,7 @@ 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,
> > !skb->xmit_more);
> >
> 
> Looks like the issue of V2 still there (E.g we need to kick when
> hv_ringbuffer_write() returns -EAGAIN?

Jason, this issue will be handled in the lower layer. I have already submitted a patch to the vmbus
Driver that correctly signals the host when EAGAIN is encountered.

Regards,

K. Y