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Re: [PATCH] skb pcount with MTU discovery

To: John Heffner <jheffner@xxxxxxx>
Subject: Re: [PATCH] skb pcount with MTU discovery
From: "David S. Miller" <davem@xxxxxxxxxxxxx>
Date: Fri, 1 Apr 2005 13:10:45 -0800
Cc: netdev@xxxxxxxxxxx
In-reply-to: <Pine.LNX.4.58.0504011340510.17051@xxxxxxxxxxxxxx>
References: <Pine.LNX.4.58.0504011340510.17051@xxxxxxxxxxxxxx>
Sender: netdev-bounce@xxxxxxxxxxx
On Fri, 1 Apr 2005 16:05:49 -0500 (EST)
John Heffner <jheffner@xxxxxxx> wrote:

> The problem is that when doing MTU discovery, the too-large segments in
> the write queue will be calculated as having a pcount of >1.  When
> tcp_write_xmit() is trying to send, tcp_snd_test() fails the cwnd test
> when pcount > cwnd.
> 
> The segments are eventually transmitted one at a time by keepalive, but
> this can take a long time.
> 
> This patch checks if TSO is enabled when setting pcount.

Why isn't the MSS properly updated at this point in time?
If it were, the pcount setting would do the right thing.

That's how this code is supposed to work.

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