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From: Alexander Duyck <alexander.duyck@gmail.com>
Date: Thu, 16 Mar 2017 15:36:21 -0700
Message-ID: <CAKgT0UeEstUeZ8J-Q9EmUvHZS1id=xND=tME9XhKjOOg+t66UQ@mail.gmail.com>
Subject: Re: [net-next PATCH 2/5] net: Call sk_mark_napi_id() in the ACK
 receive path
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Netdev <netdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "Samudrala, Sridhar" <sridhar.samudrala@intel.com>,
        Eric Dumazet <edumazet@google.com>, David Miller <davem@davemloft.net>
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On Thu, Mar 16, 2017 at 3:04 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> On Thu, 2017-03-16 at 11:32 -0700, Alexander Duyck wrote:
>> From: Sridhar Samudrala <sridhar.samudrala@intel.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@intel.com>
>> Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.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 ?

Sorry, I spaced out and overlooked that this would also be an issue for IPv6.

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

We can look into that for the next version.