hv_netvsc: Use the xmit_more skb flag to optimize signaling the host

PATCH Superseded K. Y. Srinivasan 2 participants 3 messages Apr 30, 2015 – May 6, 2015

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Networking Network drivers Hyper-V/Azure core and drivers

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K. Y. Srinivasan

author

2015-04-30 22:10 UTC #0 lore raw

PATCH v2 1/1 hv_netvsc: Use the xmit_more skb flag to optimize signaling the host

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 <[email protected]>

---
v2: Fixed up indentation based on feedback from David Miller.

 drivers/net/hyperv/netvsc.c |   20 ++++++++++++--------
 1 files changed, 12 insertions(+), 8 deletions(-)

drivers/net/hyperv/netvsc.c +12 -8

index 2e8ad06..5fdc5e1 100644
@@ -743,6 +743,7 @@ 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;
 
 	nvmsg.hdr.msg_type = NVSP_MSG1_TYPE_SEND_RNDIS_PKT;
 	if (packet->is_data_pkt) {

@@ -772,19 +773,22 @@ static inline int netvsc_send_pkt(
 	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) {

Signature · 1 line

1.7.4.1

Eric Dumazet

2015-05-01 04:36 UTC #1 lore raw

Quoted 45 lines · K. Y. Srinivasan

Signed-off-by K. Y. Srinivasan <[email protected]>

---
v2: Fixed up indentation based on feedback from David Miller.

 drivers/net/hyperv/netvsc.c |   20 ++++++++++++--------
 1 files changed, 12 insertions(+), 8 deletions(-)

drivers/net/hyperv/netvsc.c +10 -7

index 2e8ad06..5fdc5e1 100644
@@ -743,6 +743,7 @@ 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;
 
 	nvmsg.hdr.msg_type = NVSP_MSG1_TYPE_SEND_RNDIS_PKT;
 	if (packet->is_data_pkt) {

@@ -772,19 +773,22 @@ static inline int netvsc_send_pkt(
 	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(

drivers/net/hyperv/netvsc.c static inline int netvsc_send_pkt( · line 794

Quoted 10 lines

drivers/net/hyperv/netvsc.c +2 -1

+		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) {

This might be problematic, if queue is stopped ( netif_tx_stop_queue())

You need to force a kick if we are about to stop the queue :

Random example : commit ddd0ca5d60b350bbfbfb60b25885a9779ce6d6c7

KY Srinivasan

author

2015-05-06 00:08 UTC #2 lore raw

Quoted 72 lines

-----Original Message-----
From: Eric Dumazet [mailto:[email protected]]
Sent: Thursday, April 30, 2015 9:37 PM
To: KY Srinivasan
Cc: [email protected]; [email protected]; linux- [email protected]; [email protected]; [email protected]; [email protected]; [email protected]
Subject: Re: [PATCH V2 net-next 1/1] hv_netvsc: Use the xmit_more skb flag to optimize signaling the host
Quoted 2 lines · K. Y. Srinivasan
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
Quoted 1 line
make the host more efficient since it can potentially process a larger batch
of
Quoted 14 lines
packets. Implement this optimization.
Signed-off-by K. Y. Srinivasan <[email protected]>
---
v2: Fixed up indentation based on feedback from David Miller.
 drivers/net/hyperv/netvsc.c |   20 ++++++++++++--------
 1 files changed, 12 insertions(+), 8 deletions(-)
drivers/net/hyperv/netvsc.c +0 -0
index 2e8ad06..5fdc5e1 100644
drivers/net/hyperv/netvsc.c static inline int netvsc_send_pkt( · line 746
Quoted 4 lines
drivers/net/hyperv/netvsc.c +1 -0
@@ -743,6 +743,7 @@ 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;
drivers/net/hyperv/netvsc.c static inline int netvsc_send_pkt( · line 779
Quoted 12 lines
drivers/net/hyperv/netvsc.c +0 -5
 	nvmsg.hdr.msg_type = NVSP_MSG1_TYPE_SEND_RNDIS_PKT;
 	if (packet->is_data_pkt) {
@@ -772,19 +773,22 @@ static inline int netvsc_send_pkt(
 	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),
Quoted 8 lines
drivers/net/hyperv/netvsc.c +7 -1
-						  req_id);
+		ret = vmbus_sendpacket_pagebuffer_ctl(out_channel,
+						      pgbuf,
+						      packet->page_buf_cnt,
+						      &nvmsg,
+						      sizeof(struct
+							     nvsp_message),
+						      req_id,
drivers/net/hyperv/netvsc.c static inline int netvsc_send_pkt(
Quoted 10 lines
drivers/net/hyperv/netvsc.c +3 -2
+						      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);
Quoted 3 lines
drivers/net/hyperv/netvsc.c +1 -0
+				vmbus_flags, !packet->xmit_more);
 	}
 

Quoted 7 lines

drivers/net/hyperv/netvsc.c static inline int netvsc_send_pkt( · line 794
Quoted 1 line
drivers/net/hyperv/netvsc.c +0 -0
 	if (ret == 0) {
This might be problematic, if queue is stopped ( netif_tx_stop_queue())
You need to force a kick if we are about to stop the queue :
Random example : commit ddd0ca5d60b350bbfbfb60b25885a9779ce6d6c7

Thanks Eric; I will fix and resend.

Regards,

K. Y

Quoted 2 lines