netdev - Re: [PATCH net-next] tcp: Remove some spurious dropped packet profile hits from the passive connection accept path

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Date:	Thu, 20 Nov 2014 12:47:03 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Rick Jones <raj@...dy.usa.hp.com>
Cc:	netdev@...r.kernel.org, davem@...emloft.net
Subject: Re: [PATCH net-next] tcp: Remove some spurious dropped packet
 profile hits from the passive connection accept path

On Thu, 2014-11-20 at 10:58 -0800, Rick Jones wrote:
> From: Rick Jones <rick.jones2@...com>
> 
> When a system is the passive accepter of many connections, for example
> when the target of a netperf TCP_CC or TCP_CRR test, or as say a web
> server, the discard of the skb containing the TCP SYN being processed
> for the LISTEN endpoint should be a consume_skb() rather than a kfree_skb()
> to avoid cluttering a dropped packet profile.
> 
> Signed-off-by: Rick Jones <rick.jones2@...com>
> 
> ---

So what happens if we really drop the packet ?

TCP stack at this point owns the packet, it is possible to mark a bit in
it to either call consume_skb() or kfree_skb()

I attempted this once but gave up because it was a quite intrusive
patch...


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