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

-----Original Message-----
From: Jason Wang [mailto:jasowang@redhat.com]
Sent: Tuesday, March 17, 2015 8:09 PM
To: KY Srinivasan
Cc: davem@davemloft.net; netdev@vger.kernel.org; linux-
kernel@vger.kernel.org; devel@linuxdriverproject.org; olaf@aepfle.de;
apw@canonical.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 [off-list ref]
wrote:

quoted

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@microsoft.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;

quoted

 	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),

quoted

-						  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);

quoted

+				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,

quoted

 					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