netdev - Re: [net-next PATCH 2/5] net: Call sk_mark_napi

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Date:   Thu, 16 Mar 2017 15:04:53 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Alexander Duyck <alexander.duyck@...il.com>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        sridhar.samudrala@...el.com, edumazet@...gle.com,
        davem@...emloft.net
Subject: Re: [net-next PATCH 2/5] net: Call sk_mark_napi_id() in the ACK
 receive path

On Thu, 2017-03-16 at 11:32 -0700, Alexander Duyck wrote:
> From: Sridhar Samudrala <sridhar.samudrala@...el.com>
> 
> Call sk_mark_napi_id() in the ACK receive path of a TCP_NEW_SYN_RECV
> socket, so that sk->napi_id is set even if the socket hasn't yet received
> any data.  With this change we should be able to start busy polling
> slightly earlier.
> 
> Signed-off-by: Sridhar Samudrala <sridhar.samudrala@...el.com>
> Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
> ---
>  net/ipv4/tcp_ipv4.c |    1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
> index 08d870e45658..b86002a296f1 100644
> --- a/net/ipv4/tcp_ipv4.c
> +++ b/net/ipv4/tcp_ipv4.c
> @@ -1687,6 +1687,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
>  			tcp_v4_send_reset(nsk, skb);
>  			goto discard_and_relse;
>  		} else {
> +			sk_mark_napi_id(nsk, skb);
>  			sock_put(sk);
>  			return 0;
>  		}
> 

Seems good, but what about IPv6 ?

Frankly this calls for the sk_mark_napi_id() being done in
tcp_child_process() instead of its four callers.