Re: [PATCH 07/29] Use skb timestamp for receiver side

[Gerrit Renker <gerrit@erg.abdn.ac.uk>]

Same comment. Please do read the documentation accompanying the patch.

Quoting David Miller:
|  From: "Ian McDonald" <ian.mcdonald@jandi.co.nz>
|  Date: Fri, 13 Apr 2007 09:50:30 +1200
|  
|  > I didn't know this time stamping was expensive but I knew the way we
|  > were trying to optimise LAN is wrong. I say LAN because a few
|  > microseconds or even milliseconds difference on a WAN link makes
|  > bugger all difference in throughput. DCCP takes into account operating
|  > system granularity etc and if we are running lossless (i.e. receiver
|  > can cope with receiving link at full speed) then we can transmit at
|  > line speed. I've tested this myself.
|  
|  You want the scheduling delays and other issues that can
|  delay DCCP input packet processing to get factored into
|  the RTT, so that the sender will pace properly.
|  
|  Trying to get perfect timestamping and RTT measurements,
|  and ignoring scheduling delays, is quite foolhardy and shows
|  a lack of understanding of how queueing really works.
|  
|