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From: David Miller <davem@davemloft.net>
Subject: Re: reading the tcp headers within the write queue
Date: Thu, 13 Dec 2007 11:13:27 -0800 (PST)
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From: Gavin McCullagh <Gavin.McCullagh@nuim.ie>
Date: Thu, 13 Dec 2007 19:08:59 +0000

> Thought that might be it. I presume there isn't any other residue of the
> tcp options elsewhere, that one could look at when the packet gets
> acknowledged?  I'm particularly interested in the timestamp.

Every time we transmit, the timestamp will be different.

We store the jiffies at transmit time in TCP_SKB_CB(skb)->when,
so you can use that.  This is the value we use to compute the
timestamp.