* [PATCH net-next] neigh: reduce arp latency
@ 2011-08-09 15:40 Eric Dumazet
2011-08-09 17:06 ` Julian Anastasov
0 siblings, 1 reply; 4+ messages in thread
From: Eric Dumazet @ 2011-08-09 15:40 UTC (permalink / raw)
To: David Miller; +Cc: netdev
Remove the artificial HZ latency on arp resolution.
Instead of firing a timer in one jiffy (up to 10 ms if HZ=100), lets
send the ARP message immediately.
Before patch :
# arp -d 192.168.20.108 ; ping -c 3 192.168.20.108
PING 192.168.20.108 (192.168.20.108) 56(84) bytes of data.
64 bytes from 192.168.20.108: icmp_seq=1 ttl=64 time=9.91 ms
64 bytes from 192.168.20.108: icmp_seq=2 ttl=64 time=0.065 ms
64 bytes from 192.168.20.108: icmp_seq=3 ttl=64 time=0.061 ms
After patch :
$ arp -d 192.168.20.108 ; ping -c 3 192.168.20.108
PING 192.168.20.108 (192.168.20.108) 56(84) bytes of data.
64 bytes from 192.168.20.108: icmp_seq=1 ttl=64 time=0.152 ms
64 bytes from 192.168.20.108: icmp_seq=2 ttl=64 time=0.064 ms
64 bytes from 192.168.20.108: icmp_seq=3 ttl=64 time=0.074 ms
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
---
net/core/neighbour.c | 32 ++++++++++++++++++++++----------
1 file changed, 22 insertions(+), 10 deletions(-)
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 8fab9b0..d99f908 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -844,6 +844,19 @@ static void neigh_invalidate(struct neighbour *neigh)
skb_queue_purge(&neigh->arp_queue);
}
+static void neigh_probe(struct neighbour *neigh)
+ __releases(neigh->lock)
+{
+ struct sk_buff *skb = skb_peek(&neigh->arp_queue);
+ /* keep skb alive even if arp_queue overflows */
+ if (skb)
+ skb = skb_copy(skb, GFP_ATOMIC);
+ write_unlock(&neigh->lock);
+ neigh->ops->solicit(neigh, skb);
+ atomic_inc(&neigh->probes);
+ kfree_skb(skb);
+}
+
/* Called when a timer expires for a neighbour entry. */
static void neigh_timer_handler(unsigned long arg)
@@ -920,14 +933,7 @@ static void neigh_timer_handler(unsigned long arg)
neigh_hold(neigh);
}
if (neigh->nud_state & (NUD_INCOMPLETE | NUD_PROBE)) {
- struct sk_buff *skb = skb_peek(&neigh->arp_queue);
- /* keep skb alive even if arp_queue overflows */
- if (skb)
- skb = skb_copy(skb, GFP_ATOMIC);
- write_unlock(&neigh->lock);
- neigh->ops->solicit(neigh, skb);
- atomic_inc(&neigh->probes);
- kfree_skb(skb);
+ neigh_probe(neigh);
} else {
out:
write_unlock(&neigh->lock);
@@ -943,6 +949,7 @@ int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb)
{
int rc;
unsigned long now;
+ bool immediate_probe = false;
write_lock_bh(&neigh->lock);
@@ -957,7 +964,8 @@ int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb)
atomic_set(&neigh->probes, neigh->parms->ucast_probes);
neigh->nud_state = NUD_INCOMPLETE;
neigh->updated = jiffies;
- neigh_add_timer(neigh, now + 1);
+ neigh_add_timer(neigh, now + HZ);
+ immediate_probe = true;
} else {
neigh->nud_state = NUD_FAILED;
neigh->updated = jiffies;
@@ -989,7 +997,11 @@ int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb)
rc = 1;
}
out_unlock_bh:
- write_unlock_bh(&neigh->lock);
+ if (immediate_probe)
+ neigh_probe(neigh);
+ else
+ write_unlock(&neigh->lock);
+ local_bh_enable();
return rc;
}
EXPORT_SYMBOL(__neigh_event_send);
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH net-next] neigh: reduce arp latency
2011-08-09 15:40 [PATCH net-next] neigh: reduce arp latency Eric Dumazet
@ 2011-08-09 17:06 ` Julian Anastasov
2011-08-09 18:15 ` [PATCH v2 " Eric Dumazet
0 siblings, 1 reply; 4+ messages in thread
From: Julian Anastasov @ 2011-08-09 17:06 UTC (permalink / raw)
To: Eric Dumazet; +Cc: David Miller, netdev
Hello,
On Tue, 9 Aug 2011, Eric Dumazet wrote:
> Remove the artificial HZ latency on arp resolution.
>
> Instead of firing a timer in one jiffy (up to 10 ms if HZ=100), lets
> send the ARP message immediately.
>
> @@ -957,7 +964,8 @@ int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb)
> atomic_set(&neigh->probes, neigh->parms->ucast_probes);
> neigh->nud_state = NUD_INCOMPLETE;
> neigh->updated = jiffies;
> - neigh_add_timer(neigh, now + 1);
> + neigh_add_timer(neigh, now + HZ);
To be correct with old NUD_INCOMPLETE logic may be we can use
max(neigh->parms->retrans_time, HZ/2) here instead of HZ?
> + immediate_probe = true;
> } else {
> neigh->nud_state = NUD_FAILED;
> neigh->updated = jiffies;
Regards
--
Julian Anastasov <ja@ssi.bg>
^ permalink raw reply [flat|nested] 4+ messages in thread* [PATCH v2 net-next] neigh: reduce arp latency
2011-08-09 17:06 ` Julian Anastasov
@ 2011-08-09 18:15 ` Eric Dumazet
2011-08-12 9:57 ` David Miller
0 siblings, 1 reply; 4+ messages in thread
From: Eric Dumazet @ 2011-08-09 18:15 UTC (permalink / raw)
To: Julian Anastasov; +Cc: David Miller, netdev
Le mardi 09 août 2011 à 20:06 +0300, Julian Anastasov a écrit :
> To be correct with old NUD_INCOMPLETE logic may be we can use
> max(neigh->parms->retrans_time, HZ/2) here instead of HZ?
>
Thanks Julian a lot for reviewing, here is v2 adressing this point.
[PATCH v2 net-next] neigh: reduce arp latency
Remove the artificial HZ latency on arp resolution.
Instead of firing a timer in one jiffy (up to 10 ms if HZ=100), lets
send the ARP message immediately.
Before patch :
# arp -d 192.168.20.108 ; ping -c 3 192.168.20.108
PING 192.168.20.108 (192.168.20.108) 56(84) bytes of data.
64 bytes from 192.168.20.108: icmp_seq=1 ttl=64 time=9.91 ms
64 bytes from 192.168.20.108: icmp_seq=2 ttl=64 time=0.065 ms
64 bytes from 192.168.20.108: icmp_seq=3 ttl=64 time=0.061 ms
After patch :
$ arp -d 192.168.20.108 ; ping -c 3 192.168.20.108
PING 192.168.20.108 (192.168.20.108) 56(84) bytes of data.
64 bytes from 192.168.20.108: icmp_seq=1 ttl=64 time=0.152 ms
64 bytes from 192.168.20.108: icmp_seq=2 ttl=64 time=0.064 ms
64 bytes from 192.168.20.108: icmp_seq=3 ttl=64 time=0.074 ms
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
---
net/core/neighbour.c | 40 ++++++++++++++++++++++++++--------------
1 file changed, 26 insertions(+), 14 deletions(-)
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 8fab9b0..4002261 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -844,6 +844,19 @@ static void neigh_invalidate(struct neighbour *neigh)
skb_queue_purge(&neigh->arp_queue);
}
+static void neigh_probe(struct neighbour *neigh)
+ __releases(neigh->lock)
+{
+ struct sk_buff *skb = skb_peek(&neigh->arp_queue);
+ /* keep skb alive even if arp_queue overflows */
+ if (skb)
+ skb = skb_copy(skb, GFP_ATOMIC);
+ write_unlock(&neigh->lock);
+ neigh->ops->solicit(neigh, skb);
+ atomic_inc(&neigh->probes);
+ kfree_skb(skb);
+}
+
/* Called when a timer expires for a neighbour entry. */
static void neigh_timer_handler(unsigned long arg)
@@ -920,14 +933,7 @@ static void neigh_timer_handler(unsigned long arg)
neigh_hold(neigh);
}
if (neigh->nud_state & (NUD_INCOMPLETE | NUD_PROBE)) {
- struct sk_buff *skb = skb_peek(&neigh->arp_queue);
- /* keep skb alive even if arp_queue overflows */
- if (skb)
- skb = skb_copy(skb, GFP_ATOMIC);
- write_unlock(&neigh->lock);
- neigh->ops->solicit(neigh, skb);
- atomic_inc(&neigh->probes);
- kfree_skb(skb);
+ neigh_probe(neigh);
} else {
out:
write_unlock(&neigh->lock);
@@ -942,7 +948,7 @@ out:
int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb)
{
int rc;
- unsigned long now;
+ bool immediate_probe = false;
write_lock_bh(&neigh->lock);
@@ -950,14 +956,16 @@ int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb)
if (neigh->nud_state & (NUD_CONNECTED | NUD_DELAY | NUD_PROBE))
goto out_unlock_bh;
- now = jiffies;
-
if (!(neigh->nud_state & (NUD_STALE | NUD_INCOMPLETE))) {
if (neigh->parms->mcast_probes + neigh->parms->app_probes) {
+ unsigned long next, now = jiffies;
+
atomic_set(&neigh->probes, neigh->parms->ucast_probes);
neigh->nud_state = NUD_INCOMPLETE;
- neigh->updated = jiffies;
- neigh_add_timer(neigh, now + 1);
+ neigh->updated = now;
+ next = now + max(neigh->parms->retrans_time, HZ/2);
+ neigh_add_timer(neigh, next);
+ immediate_probe = true;
} else {
neigh->nud_state = NUD_FAILED;
neigh->updated = jiffies;
@@ -989,7 +997,11 @@ int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb)
rc = 1;
}
out_unlock_bh:
- write_unlock_bh(&neigh->lock);
+ if (immediate_probe)
+ neigh_probe(neigh);
+ else
+ write_unlock(&neigh->lock);
+ local_bh_enable();
return rc;
}
EXPORT_SYMBOL(__neigh_event_send);
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH v2 net-next] neigh: reduce arp latency
2011-08-09 18:15 ` [PATCH v2 " Eric Dumazet
@ 2011-08-12 9:57 ` David Miller
0 siblings, 0 replies; 4+ messages in thread
From: David Miller @ 2011-08-12 9:57 UTC (permalink / raw)
To: eric.dumazet; +Cc: ja, netdev
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Tue, 09 Aug 2011 20:15:58 +0200
> Le mardi 09 août 2011 à 20:06 +0300, Julian Anastasov a écrit :
>
>> To be correct with old NUD_INCOMPLETE logic may be we can use
>> max(neigh->parms->retrans_time, HZ/2) here instead of HZ?
>>
>
> Thanks Julian a lot for reviewing, here is v2 adressing this point.
>
> [PATCH v2 net-next] neigh: reduce arp latency
>
> Remove the artificial HZ latency on arp resolution.
>
> Instead of firing a timer in one jiffy (up to 10 ms if HZ=100), lets
> send the ARP message immediately.
>
> Before patch :
>
> # arp -d 192.168.20.108 ; ping -c 3 192.168.20.108
> PING 192.168.20.108 (192.168.20.108) 56(84) bytes of data.
> 64 bytes from 192.168.20.108: icmp_seq=1 ttl=64 time=9.91 ms
> 64 bytes from 192.168.20.108: icmp_seq=2 ttl=64 time=0.065 ms
> 64 bytes from 192.168.20.108: icmp_seq=3 ttl=64 time=0.061 ms
>
> After patch :
>
> $ arp -d 192.168.20.108 ; ping -c 3 192.168.20.108
> PING 192.168.20.108 (192.168.20.108) 56(84) bytes of data.
> 64 bytes from 192.168.20.108: icmp_seq=1 ttl=64 time=0.152 ms
> 64 bytes from 192.168.20.108: icmp_seq=2 ttl=64 time=0.064 ms
> 64 bytes from 192.168.20.108: icmp_seq=3 ttl=64 time=0.074 ms
>
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Applied.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2011-08-09 15:40 [PATCH net-next] neigh: reduce arp latency Eric Dumazet
2011-08-09 17:06 ` Julian Anastasov
2011-08-09 18:15 ` [PATCH v2 " Eric Dumazet
2011-08-12 9:57 ` David Miller
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