netdev - Re: [PATCH net-next] neigh: reduce arp latency

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Message-ID: <alpine.LFD.2.00.1108091959250.1527@ja.ssi.bg>
Date:	Tue, 9 Aug 2011 20:06:25 +0300 (EEST)
From:	Julian Anastasov <ja@....bg>
To:	Eric Dumazet <eric.dumazet@...il.com>
cc:	David Miller <davem@...emloft.net>, netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] neigh: reduce arp latency


	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@....bg>
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