* [PATCH] net: core: improve the tx_hash calculating
@ 2018-05-31 10:14 Tonghao Zhang
2018-06-01 8:58 ` Sergei Shtylyov
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Tonghao Zhang @ 2018-05-31 10:14 UTC (permalink / raw)
To: netdev; +Cc: Tonghao Zhang
Use the % instead of while, and it may simple code and improve
the calculating. The real_num_tx_queues has been checked when
allocating and setting it.
Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
---
net/core/dev.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index 1844d9b..edc5b75 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2617,15 +2617,13 @@ void netif_device_attach(struct net_device *dev)
*/
static u16 skb_tx_hash(const struct net_device *dev, struct sk_buff *skb)
{
- u32 hash;
u16 qoffset = 0;
u16 qcount = dev->real_num_tx_queues;
if (skb_rx_queue_recorded(skb)) {
- hash = skb_get_rx_queue(skb);
- while (unlikely(hash >= qcount))
- hash -= qcount;
- return hash;
+ /* When setting the real_num_tx_queues, we make sure
+ * real_num_tx_queues != 0. */
+ return skb_get_rx_queue(skb) % qcount;
}
if (dev->num_tc) {
--
1.8.3.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] net: core: improve the tx_hash calculating
2018-05-31 10:14 [PATCH] net: core: improve the tx_hash calculating Tonghao Zhang
@ 2018-06-01 8:58 ` Sergei Shtylyov
2018-06-01 9:54 ` Eric Dumazet
2018-06-01 17:27 ` David Miller
2 siblings, 0 replies; 4+ messages in thread
From: Sergei Shtylyov @ 2018-06-01 8:58 UTC (permalink / raw)
To: Tonghao Zhang, netdev
Hello!
On 5/31/2018 1:14 PM, Tonghao Zhang wrote:
> Use the % instead of while, and it may simple code and improve
> the calculating. The real_num_tx_queues has been checked when
> allocating and setting it.
>
> Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
> ---
> net/core/dev.c | 8 +++-----
> 1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 1844d9b..edc5b75 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -2617,15 +2617,13 @@ void netif_device_attach(struct net_device *dev)
> */
> static u16 skb_tx_hash(const struct net_device *dev, struct sk_buff *skb)
> {
> - u32 hash;
> u16 qoffset = 0;
> u16 qcount = dev->real_num_tx_queues;
>
> if (skb_rx_queue_recorded(skb)) {
> - hash = skb_get_rx_queue(skb);
> - while (unlikely(hash >= qcount))
> - hash -= qcount;
> - return hash;
> + /* When setting the real_num_tx_queues, we make sure
> + * real_num_tx_queues != 0. */
In the networking code, multiline comments should look like:
/* bla
* bla
*/
> + return skb_get_rx_queue(skb) % qcount;
> }
>
> if (dev->num_tc) {
MBR, Sergei
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] net: core: improve the tx_hash calculating
2018-05-31 10:14 [PATCH] net: core: improve the tx_hash calculating Tonghao Zhang
2018-06-01 8:58 ` Sergei Shtylyov
@ 2018-06-01 9:54 ` Eric Dumazet
2018-06-01 17:27 ` David Miller
2 siblings, 0 replies; 4+ messages in thread
From: Eric Dumazet @ 2018-06-01 9:54 UTC (permalink / raw)
To: Tonghao Zhang, netdev
On 05/31/2018 06:14 AM, Tonghao Zhang wrote:
> Use the % instead of while, and it may simple code and improve
> the calculating. The real_num_tx_queues has been checked when
> allocating and setting it.
>
> Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
> ---
> net/core/dev.c | 8 +++-----
> 1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 1844d9b..edc5b75 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -2617,15 +2617,13 @@ void netif_device_attach(struct net_device *dev)
> */
> static u16 skb_tx_hash(const struct net_device *dev, struct sk_buff *skb)
> {
> - u32 hash;
> u16 qoffset = 0;
> u16 qcount = dev->real_num_tx_queues;
>
> if (skb_rx_queue_recorded(skb)) {
> - hash = skb_get_rx_queue(skb);
> - while (unlikely(hash >= qcount))
> - hash -= qcount;
> - return hash;
> + /* When setting the real_num_tx_queues, we make sure
> + * real_num_tx_queues != 0. */
> + return skb_get_rx_queue(skb) % qcount;
> }
>
> if (dev->num_tc) {
>
This patch is adding a divide. We do not need it most of the time.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] net: core: improve the tx_hash calculating
2018-05-31 10:14 [PATCH] net: core: improve the tx_hash calculating Tonghao Zhang
2018-06-01 8:58 ` Sergei Shtylyov
2018-06-01 9:54 ` Eric Dumazet
@ 2018-06-01 17:27 ` David Miller
2 siblings, 0 replies; 4+ messages in thread
From: David Miller @ 2018-06-01 17:27 UTC (permalink / raw)
To: xiangxia.m.yue; +Cc: netdev
From: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Date: Thu, 31 May 2018 03:14:01 -0700
> Use the % instead of while, and it may simple code and improve
> the calculating. The real_num_tx_queues has been checked when
> allocating and setting it.
>
> Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
The loop is there to avoid the expensive modulus operation,
not to avoid the real_num_tx_queues == 0 case.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2018-05-31 10:14 [PATCH] net: core: improve the tx_hash calculating Tonghao Zhang
2018-06-01 8:58 ` Sergei Shtylyov
2018-06-01 9:54 ` Eric Dumazet
2018-06-01 17:27 ` David Miller
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