netdev - Re: why does skb->tstamp use getnstimeofday?

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Date:	Mon, 16 Jan 2012 14:05:21 -0800
From:	Rick Jones <rick.jones2@...com>
To:	Anatoly Sivov <mm05@...l.ru>
CC:	Eric Dumazet <eric.dumazet@...il.com>, netdev@...r.kernel.org
Subject: Re: why does skb->tstamp use getnstimeofday?

On 01/15/2012 09:55 AM, Anatoly Sivov wrote:
> I missed that field tstamp is used for things other than RTT and can be
> even user-spaced with SO_TIMESTAMP.
> However, timekeeper speed up/slow down (due to ntp) can seriously affect
> some congestion avoidance algorithm quality, I guess.
> Am I wrong?

Good question - not sure if we will see anything, but the upcoming 
leap-second might be interesting to watch - though I think contemporary 
NTP addresses that by a big slew rather than a step adjust.  Of course 
it can step-adjust the time on the system, but 99 times out of 10 (*) 
that will be just at system start-up, when there probably will not be 
all that many congestion controlled connections active.  Of course, who 
knows what that 100th out of 10 times will do.

rick jones
* 99 times out of 10 is an expression which if I recall correctly was 
coined or at least repeated by a high-school sports coach to mean 
"virtually all of the time"
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