netdev - Re: [PATCH] apply cwnd rules to FIN packets with data

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Message-ID: <45C7B77B.9060506@psc.edu>
Date:	Mon, 05 Feb 2007 18:02:19 -0500
From:	John Heffner <jheffner@....edu>
To:	David Miller <davem@...emloft.net>
CC:	netdev@...r.kernel.org
Subject: Re: [PATCH] apply cwnd rules to FIN packets with data

David Miller wrote:
> From: John Heffner <jheffner@....edu>
> Date: Mon, 05 Feb 2007 16:58:18 -0500
> 
>> This is especially important with TSO enabled.  Currently, it will send 
>> a burst of up to 64k at the end of a connection, even when cwnd is much 
>> smaller than 64k.  This patch still lets out empty FIN packets, but does 
>> not apply the special case to FINs carrying data.
> 
> Good catch John.
> 
> But I think the correct test on skb->len would be to just make
> sure that it is <= REAL_MSS.
> 
> What do you think about that?  This would match the original intention
> of the logic in the pre-TSO days.

What was the intention of that logic?

Actually, I think it would be better to leave the Nagle test as it was 
(which is implicitly < real_mss), because there is obviously no point in 
doing the nagle test when you know there is no more data that will be 
sent.  However, I can't think of any reason why the cwnd test should not 
apply.

   -John
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