* [PATCH] net: rps: add the shortcut for one rps_cpus
@ 2010-09-04 9:12 Changli Gao
2010-09-04 11:01 ` Eric Dumazet
0 siblings, 1 reply; 4+ messages in thread
From: Changli Gao @ 2010-09-04 9:12 UTC (permalink / raw)
To: David S. Miller; +Cc: netdev, Changli Gao
When there is only one rps_cpus, skb_get_rxhash() can be eliminated.
Signed-off-by: Changli Gao <xiaosuo@gmail.com>
---
net/core/dev.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index d8c43e7..2bf740c 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2345,7 +2345,7 @@ static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
struct rps_dev_flow **rflowp)
{
struct netdev_rx_queue *rxqueue;
- struct rps_map *map;
+ struct rps_map *map = NULL;
struct rps_dev_flow_table *flow_table;
struct rps_sock_flow_table *sock_flow_table;
int cpu = -1;
@@ -2363,8 +2363,17 @@ static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
} else
rxqueue = dev->_rx;
- if (!rxqueue->rps_map && !rxqueue->rps_flow_table)
+ if (rxqueue->rps_map) {
+ map = rcu_dereference(rxqueue->rps_map);
+ if (map && map->len == 1) {
+ tcpu = map->cpus[0];
+ if (cpu_online(tcpu))
+ cpu = tcpu;
+ goto done;
+ }
+ } else if (!rxqueue->rps_flow_table) {
goto done;
+ }
skb_reset_network_header(skb);
if (!skb_get_rxhash(skb))
@@ -2409,7 +2418,6 @@ static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
}
}
- map = rcu_dereference(rxqueue->rps_map);
if (map) {
tcpu = map->cpus[((u64) skb->rxhash * map->len) >> 32];
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] net: rps: add the shortcut for one rps_cpus
2010-09-04 9:12 [PATCH] net: rps: add the shortcut for one rps_cpus Changli Gao
@ 2010-09-04 11:01 ` Eric Dumazet
2010-09-04 12:18 ` Changli Gao
0 siblings, 1 reply; 4+ messages in thread
From: Eric Dumazet @ 2010-09-04 11:01 UTC (permalink / raw)
To: Changli Gao; +Cc: David S. Miller, netdev
Le samedi 04 septembre 2010 à 17:12 +0800, Changli Gao a écrit :
> When there is only one rps_cpus, skb_get_rxhash() can be eliminated.
>
> Signed-off-by: Changli Gao <xiaosuo@gmail.com>
> ---
> net/core/dev.c | 14 +++++++++++---
> 1 file changed, 11 insertions(+), 3 deletions(-)
> diff --git a/net/core/dev.c b/net/core/dev.c
> index d8c43e7..2bf740c 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -2345,7 +2345,7 @@ static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
> struct rps_dev_flow **rflowp)
> {
> struct netdev_rx_queue *rxqueue;
> - struct rps_map *map;
> + struct rps_map *map = NULL;
> struct rps_dev_flow_table *flow_table;
> struct rps_sock_flow_table *sock_flow_table;
> int cpu = -1;
> @@ -2363,8 +2363,17 @@ static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
> } else
> rxqueue = dev->_rx;
>
> - if (!rxqueue->rps_map && !rxqueue->rps_flow_table)
> + if (rxqueue->rps_map) {
> + map = rcu_dereference(rxqueue->rps_map);
> + if (map && map->len == 1) {
> + tcpu = map->cpus[0];
> + if (cpu_online(tcpu))
> + cpu = tcpu;
> + goto done;
> + }
> + } else if (!rxqueue->rps_flow_table) {
> goto done;
> + }
>
> skb_reset_network_header(skb);
> if (!skb_get_rxhash(skb))
> @@ -2409,7 +2418,6 @@ static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
> }
> }
>
> - map = rcu_dereference(rxqueue->rps_map);
> if (map) {
> tcpu = map->cpus[((u64) skb->rxhash * map->len) >> 32];
>
> --
You are 'optimizing' a very unusual case and slow down 99% of normal
uses.
Normal way to handle this, is to use irq affinity and deliver interrupts
directly to the target cpu.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] net: rps: add the shortcut for one rps_cpus
2010-09-04 11:01 ` Eric Dumazet
@ 2010-09-04 12:18 ` Changli Gao
2010-09-08 20:11 ` David Miller
0 siblings, 1 reply; 4+ messages in thread
From: Changli Gao @ 2010-09-04 12:18 UTC (permalink / raw)
To: Eric Dumazet; +Cc: David S. Miller, netdev
On Sat, Sep 4, 2010 at 7:01 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> You are 'optimizing' a very unusual case and slow down 99% of normal
> uses.
>
> Normal way to handle this, is to use irq affinity and deliver interrupts
> directly to the target cpu.
>
>
Some pseudo network devices may share the same interrupt, such as vlan
network devices. In this case, setting the IRQ affinity can't work.
--
Regards,
Changli Gao(xiaosuo@gmail.com)
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] net: rps: add the shortcut for one rps_cpus
2010-09-04 12:18 ` Changli Gao
@ 2010-09-08 20:11 ` David Miller
0 siblings, 0 replies; 4+ messages in thread
From: David Miller @ 2010-09-08 20:11 UTC (permalink / raw)
To: xiaosuo; +Cc: eric.dumazet, netdev
From: Changli Gao <xiaosuo@gmail.com>
Date: Sat, 4 Sep 2010 20:18:20 +0800
> On Sat, Sep 4, 2010 at 7:01 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
>> You are 'optimizing' a very unusual case and slow down 99% of normal
>> uses.
>>
>> Normal way to handle this, is to use irq affinity and deliver interrupts
>> directly to the target cpu.
>>
>>
>
> Some pseudo network devices may share the same interrupt, such as vlan
> network devices. In this case, setting the IRQ affinity can't work.
I'm fine with this patch being in net-next-2.6 for now, so I've
applied it, thanks.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2010-09-08 20:11 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2010-09-04 9:12 [PATCH] net: rps: add the shortcut for one rps_cpus Changli Gao
2010-09-04 11:01 ` Eric Dumazet
2010-09-04 12:18 ` Changli Gao
2010-09-08 20:11 ` David Miller
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