Re: [PATCH net-next 1/1] forcedeth: remove redudant assignments in xmit

[David Miller]

From: Zhu Yanjun 
Date: Fri, 10 Nov 2017 21:10:00 -0500

> In xmit process, the variables are set many times. In fact,
> it is enough for these variables to be set once.
> After a long time test, the throughput performance is better
> than before.
> 
> CC: Srinivas Eeda 
> CC: Joe Jin 
> CC: Junxiao Bi 
> Signed-off-by: Zhu Yanjun 

Applied.

[PATCH net-next 1/1] forcedeth: remove redudant assignments in xmit

[Zhu Yanjun]

In xmit process, the variables are set many times. In fact,
it is enough for these variables to be set once.
After a long time test, the throughput performance is better
than before.

CC: Srinivas Eeda 
CC: Joe Jin 
CC: Junxiao Bi 
Signed-off-by: Zhu Yanjun 
---
 drivers/net/ethernet/nvidia/forcedeth.c | 28 
 1 file changed, 20 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/nvidia/forcedeth.c 
b/drivers/net/ethernet/nvidia/forcedeth.c
index 63a9e1e..22912e7 100644
--- a/drivers/net/ethernet/nvidia/forcedeth.c
+++ b/drivers/net/ethernet/nvidia/forcedeth.c
@@ -2218,8 +2218,6 @@ static netdev_tx_t nv_start_xmit(struct sk_buff *skb, 
struct net_device *dev)
 
/* setup the header buffer */
do {
-   prev_tx = put_tx;
-   prev_tx_ctx = np->put_tx_ctx;
bcnt = (size > NV_TX2_TSO_MAX_SIZE) ? NV_TX2_TSO_MAX_SIZE : 
size;
np->put_tx_ctx->dma = dma_map_single(>pci_dev->dev,
 skb->data + offset, bcnt,
@@ -2254,8 +2252,6 @@ static netdev_tx_t nv_start_xmit(struct sk_buff *skb, 
struct net_device *dev)
offset = 0;
 
do {
-   prev_tx = put_tx;
-   prev_tx_ctx = np->put_tx_ctx;
if (!start_tx_ctx)
start_tx_ctx = tmp_tx_ctx = np->put_tx_ctx;
 
@@ -2296,6 +2292,16 @@ static netdev_tx_t nv_start_xmit(struct sk_buff *skb, 
struct net_device *dev)
} while (frag_size);
}
 
+   if (unlikely(put_tx == np->first_tx.orig))
+   prev_tx = np->last_tx.orig;
+   else
+   prev_tx = put_tx - 1;
+
+   if (unlikely(np->put_tx_ctx == np->first_tx_ctx))
+   prev_tx_ctx = np->last_tx_ctx;
+   else
+   prev_tx_ctx = np->put_tx_ctx - 1;
+
/* set last fragment flag  */
prev_tx->flaglen |= cpu_to_le32(tx_flags_extra);
 
@@ -2368,8 +2374,6 @@ static netdev_tx_t nv_start_xmit_optimized(struct sk_buff 
*skb,
 
/* setup the header buffer */
do {
-   prev_tx = put_tx;
-   prev_tx_ctx = np->put_tx_ctx;
bcnt = (size > NV_TX2_TSO_MAX_SIZE) ? NV_TX2_TSO_MAX_SIZE : 
size;
np->put_tx_ctx->dma = dma_map_single(>pci_dev->dev,
 skb->data + offset, bcnt,
@@ -2405,8 +2409,6 @@ static netdev_tx_t nv_start_xmit_optimized(struct sk_buff 
*skb,
offset = 0;
 
do {
-   prev_tx = put_tx;
-   prev_tx_ctx = np->put_tx_ctx;
bcnt = (frag_size > NV_TX2_TSO_MAX_SIZE) ? 
NV_TX2_TSO_MAX_SIZE : frag_size;
if (!start_tx_ctx)
start_tx_ctx = tmp_tx_ctx = np->put_tx_ctx;
@@ -2447,6 +2449,16 @@ static netdev_tx_t nv_start_xmit_optimized(struct 
sk_buff *skb,
} while (frag_size);
}
 
+   if (unlikely(put_tx == np->first_tx.ex))
+   prev_tx = np->last_tx.ex;
+   else
+   prev_tx = put_tx - 1;
+
+   if (unlikely(np->put_tx_ctx == np->first_tx_ctx))
+   prev_tx_ctx = np->last_tx_ctx;
+   else
+   prev_tx_ctx = np->put_tx_ctx - 1;
+
/* set last fragment flag  */
prev_tx->flaglen |= cpu_to_le32(NV_TX2_LASTPACKET);
 
-- 
2.7.4