* [PATCH net-next 1/2] net: tap: replay while() loop with % operator in tap_get_queue()
@ 2017-12-11 13:26 yuan linyu
2017-12-11 16:58 ` Stephen Hemminger
0 siblings, 1 reply; 3+ messages in thread
From: yuan linyu @ 2017-12-11 13:26 UTC (permalink / raw)
To: netdev; +Cc: David S . Miller, yuan linyu
From: yuan linyu <Linyu.Yuan@alcatel-sbell.com.cn>
Signed-off-by: yuan linyu <Linyu.Yuan@alcatel-sbell.com.cn>
---
drivers/net/tap.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)
diff --git a/drivers/net/tap.c b/drivers/net/tap.c
index 0a886fda..78900a0 100644
--- a/drivers/net/tap.c
+++ b/drivers/net/tap.c
@@ -275,11 +275,7 @@ static struct tap_queue *tap_get_queue(struct tap_dev *tap,
if (likely(skb_rx_queue_recorded(skb))) {
rxq = skb_get_rx_queue(skb);
-
- while (unlikely(rxq >= numvtaps))
- rxq -= numvtaps;
-
- queue = rcu_dereference(tap->taps[rxq]);
+ queue = rcu_dereference(tap->taps[rxq % numvtaps]);
goto out;
}
--
2.7.4
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH net-next 1/2] net: tap: replay while() loop with % operator in tap_get_queue()
2017-12-11 13:26 [PATCH net-next 1/2] net: tap: replay while() loop with % operator in tap_get_queue() yuan linyu
@ 2017-12-11 16:58 ` Stephen Hemminger
2017-12-11 17:02 ` David Miller
0 siblings, 1 reply; 3+ messages in thread
From: Stephen Hemminger @ 2017-12-11 16:58 UTC (permalink / raw)
To: yuan linyu; +Cc: netdev, David S . Miller, yuan linyu
On Mon, 11 Dec 2017 21:26:41 +0800
yuan linyu <cugyly@163.com> wrote:
> From: yuan linyu <Linyu.Yuan@alcatel-sbell.com.cn>
>
> Signed-off-by: yuan linyu <Linyu.Yuan@alcatel-sbell.com.cn>
> ---
> drivers/net/tap.c | 6 +-----
> 1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/drivers/net/tap.c b/drivers/net/tap.c
> index 0a886fda..78900a0 100644
> --- a/drivers/net/tap.c
> +++ b/drivers/net/tap.c
> @@ -275,11 +275,7 @@ static struct tap_queue *tap_get_queue(struct tap_dev *tap,
>
> if (likely(skb_rx_queue_recorded(skb))) {
> rxq = skb_get_rx_queue(skb);
> -
> - while (unlikely(rxq >= numvtaps))
> - rxq -= numvtaps;
> -
> - queue = rcu_dereference(tap->taps[rxq]);
> + queue = rcu_dereference(tap->taps[rxq % numvtaps]);
> goto out;
> }
>
Modulus is slower than the loop.
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH net-next 1/2] net: tap: replay while() loop with % operator in tap_get_queue()
2017-12-11 16:58 ` Stephen Hemminger
@ 2017-12-11 17:02 ` David Miller
0 siblings, 0 replies; 3+ messages in thread
From: David Miller @ 2017-12-11 17:02 UTC (permalink / raw)
To: stephen; +Cc: cugyly, netdev, Linyu.Yuan
From: Stephen Hemminger <stephen@networkplumber.org>
Date: Mon, 11 Dec 2017 08:58:11 -0800
> On Mon, 11 Dec 2017 21:26:41 +0800
> yuan linyu <cugyly@163.com> wrote:
>
>> From: yuan linyu <Linyu.Yuan@alcatel-sbell.com.cn>
>>
>> Signed-off-by: yuan linyu <Linyu.Yuan@alcatel-sbell.com.cn>
>> ---
>> drivers/net/tap.c | 6 +-----
>> 1 file changed, 1 insertion(+), 5 deletions(-)
>>
>> diff --git a/drivers/net/tap.c b/drivers/net/tap.c
>> index 0a886fda..78900a0 100644
>> --- a/drivers/net/tap.c
>> +++ b/drivers/net/tap.c
>> @@ -275,11 +275,7 @@ static struct tap_queue *tap_get_queue(struct tap_dev *tap,
>>
>> if (likely(skb_rx_queue_recorded(skb))) {
>> rxq = skb_get_rx_queue(skb);
>> -
>> - while (unlikely(rxq >= numvtaps))
>> - rxq -= numvtaps;
>> -
>> - queue = rcu_dereference(tap->taps[rxq]);
>> + queue = rcu_dereference(tap->taps[rxq % numvtaps]);
>> goto out;
>> }
>>
>
> Modulus is slower than the loop.
Agreed, the loop is there intentionally. We do this in other areas of
the kernel as well.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2017-12-11 17:02 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
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2017-12-11 13:26 [PATCH net-next 1/2] net: tap: replay while() loop with % operator in tap_get_queue() yuan linyu
2017-12-11 16:58 ` Stephen Hemminger
2017-12-11 17:02 ` David Miller
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