Message-ID: <519BCA37.4020707@linux.intel.com>
Date: Tue, 21 May 2013 22:25:43 +0300
From: Eliezer Tamir <eliezer.tamir@linux.intel.com>
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To: Eric Dumazet <eric.dumazet@gmail.com>
CC: Pekka Riikonen <priikone@iki.fi>, Dave Miller <davem@davemloft.net>,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        Jesse Brandeburg <jesse.brandeburg@intel.com>,
        Don Skidmore <donald.c.skidmore@intel.com>,
        e1000-devel@lists.sourceforge.net,
        Willem de Bruijn <willemb@google.com>,
        Andi Kleen <andi@firstfloor.org>, HPA <hpa@zytor.com>,
        Eliezer Tamir <eliezer@tamir.org.il>
Subject: Re: [PATCH v3 net-next 1/4] net: implement support for low latency
 socket polling
References: <20130520101552.14133.45953.stgit@ladj378.jer.intel.com>  <20130520101601.14133.874.stgit@ladj378.jer.intel.com>  <1369063764.3301.182.camel@edumazet-glaptop>  <519B2237.20204@linux.intel.com>  <1369142926.3301.213.camel@edumazet-glaptop>  <alpine.GSO.2.00.1305211855120.9230@git.silcnet.org>  <1369158499.3301.236.camel@edumazet-glaptop> <1369158686.3301.237.camel@edumazet-glaptop>
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On 21/05/2013 20:51, Eric Dumazet wrote:
> On Tue, 2013-05-21 at 10:48 -0700, Eric Dumazet wrote:
>
>> We do not keep skb->dev information once a packet leaves the rcu
>> protected region.
>>
>> Once packet is queued to tcp input queues, skb->dev is NULL.
>
> This is done in tcp_v4_rcv() & tcp_v6_rcv()

So if we move calling sk_mark_ll() into the rcu protected region,
We would not need the gen id in the skb.
We could save skb->dev and skb->queue_mapping along with the generation 
id in the socket.

then we don't need to change the skb struct at all.
skb_mark_ll() can go away.
we also call sk_mark_ll in one central place in net_protocol->handler 
instead of all over the place.

or am I missing something?
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