Hi Aaron,
about the 5% loss with the wndr, please remember that the shaper works
typically on raw Ethernet rates, while flent reports TCP good put I believe. So
roughly 2 to 6 percent difference can be explained with a combination of the
following overheads: PTM/ATM, ethernet, VLAN(s), PPPoE, IPv4/IPv6, TCP,
potential TCP options like timestamps... Now flent might report actual
tcp-rates and I am out to lunch, but I have a hard time reconciling how
flent/netperf, can actually learn about all the additional overhead... As far
as I can tell all netperf sees is the payload it sends and the payload it
receives...
Tl;dr: Overhead unknown to flent effortlessly explains why the TCP good put as
reported by flent falls short of the shaped rate as that rate contains all
overheads.
Best Regards
Sebastian
On June 3, 2015 7:45:47 AM GMT+02:00, Aaron Wood <[email protected]> wrote:
>I wrote this up on my blog, where I can intersperse text and graphs a
>bit
>better:
>
>http://burntchrome.blogspot.com/2015/06/htb-rate-limiting-not-quite-lining-up.html
>
>Basically, I ran a series of tcp_download tests, using increasing
>ingress
>rates with sqm_scripts, and then used flent's box-plots to put the
>results
>into a combined image for comparing.
>
>On the 3800, it never meets the rate, but it's only off by maybe 5%.
>But
>on my new WRT1900AC, it's wildly off, even over the same performance
>range
>(I tested it from 80-220Mbps rates in 20Mbps jumps, and saw from
>40-150Mbps.
>
>I have no idea where to start looking for the cause. But for now, I'm
>just
>setting my ingress rate MUCH higher than I should, because it's working
>out
>to the right value as a result.
>
>-Aaron
>
>
>------------------------------------------------------------------------
>
>_______________________________________________
>Cerowrt-devel mailing list
>[email protected]
>https://lists.bufferbloat.net/listinfo/cerowrt-devel
--
Sent from my Android device with K-9 Mail. Please excuse my brevity._______________________________________________
Cerowrt-devel mailing list
[email protected]
https://lists.bufferbloat.net/listinfo/cerowrt-devel
