netdev - Re: [PATCH RFC net-next 2/7] net: add dst_pending

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Message-ID: <1482164252.1521.7.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Mon, 19 Dec 2016 08:17:32 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Julian Anastasov <ja@....bg>
Cc:     netdev@...r.kernel.org, linux-sctp@...r.kernel.org,
        YueHaibing <yuehaibing@...wei.com>
Subject: Re: [PATCH RFC net-next 2/7] net: add dst_pending_confirm flag to
 skbuff

On Sun, 2016-12-18 at 22:56 +0200, Julian Anastasov wrote:

>  
> +static inline void sock_confirm_neigh(struct sk_buff *skb, struct neighbour *n)
> +{
> +	if (unlikely(skb->dst_pending_confirm)) {
> +		struct sock *sk = skb->sk;
> +		unsigned long now = jiffies;
> +
> +		/* avoid dirtying neighbour */
> +		if (n->confirmed != now)
> +			n->confirmed = now;
> +		if (sk && sk->sk_dst_pending_confirm)
> +			sk->sk_dst_pending_confirm = 0;
> +	}
> +}
> +

I am still digesting this awesome patch series ;)

Not sure why you used an unlikely() here. TCP for example would hit this
path quite often.

So considering sk_dst_pending_confirm might be dirtied quite often,

I am not sure why you placed it in the cache line that contains
sk_rx_dst (in 1st patch)

Thanks.