Hi,

2015-04-23 8:48 GMT+02:00 Eric Dumazet <eric.dumazet@gmail.com>:

> Wait, this is a 15 years old experiment using Reno and a single test
> bed, using ns simulator.
>
> Naive TCP pacing implementations were tried, and probably failed.
>
> Pacing individual packet is quite bad, this is the first lesson one
> learns when implementing TCP pacing, especially if you try to drive a
> 40Gbps NIC.
>
> https://lwn.net/Articles/564978/
>
> Also note we use usec based rtt samples, and nanosec high resolution
> timers in fq. I suspect the ns simulator experiment had sync issues
> because of using low resolution timers or simulation artifact, without
> any jitter source.
>
> Billions of flows are now 'paced', but keep in mind most packets are not
> paced. We do not pace in slow start, and we do not pace when tcp is ACK
> clocked.
>

We did an extensive work on the Pacing in slow start and notably during a
large IW transmission.
Benefits are really outstanding! Our last implementation is just a slight
modification of FQ/pacing

   - Sallantin, R.; Baudoin, C.; Chaput, E.; Arnal, F.; Dubois, E.; Beylot,
   A.-L., "Initial spreading: A fast Start-Up TCP mechanism," *Local
   Computer Networks (LCN), 2013 IEEE 38th Conference on* , vol., no.,
   pp.492,499, 21-24 Oct. 2013


   - Sallantin, R.; Baudoin, C.; Chaput, E.; Arnal, F.; Dubois, E.; Beylot,
   A.-L., "A TCP model for short-lived flows to validate initial
spreading," *Local
   Computer Networks (LCN), 2014 IEEE 39th Conference on* , vol., no.,
   pp.177,184, 8-11 Sept. 2014


   -

   draft-sallantin-tcpm-initial-spreading, safe increase of the TCP's IW


Did you consider using it or something similar?



>
> Only when someones sets SO_MAX_PACING_RATE below the TCP rate, we can
> eventually have all packets being paced, using TSO 'clusters' for TCP.
>
>
>
> On Thu, 2015-04-23 at 07:27 +0200, MUSCARIELLO Luca IMT/OLN wrote:
> > one reference with pdf publicly available. On the website there are
> > various papers
> > on this topic. Others might me more relevant but I did not check all of
> > them.
>
> > Understanding the Performance of TCP Pacing,
> > Amit Aggarwal, Stefan Savage, and Tom Anderson,
> > IEEE INFOCOM 2000 Tel-Aviv, Israel, March 2000, pages 1157-1165.
> >
> > http://www.cs.ucsd.edu/~savage/papers/Infocom2000pacing.pdf
>
>
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