<html><head></head><body>Hi Aaron,<br>
<br>
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...<br>
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.<br>
<br>
<br>
Best Regards<br>
Sebastian<br><br><div class="gmail_quote">On June 3, 2015 7:45:47 AM GMT+02:00, Aaron Wood <woody77@gmail.com> wrote:<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div dir="ltr"><div>I wrote this up on my blog, where I can intersperse text and graphs a bit better:</div><div><br /></div><a href="http://burntchrome.blogspot.com/2015/06/htb-rate-limiting-not-quite-lining-up.html">http://burntchrome.blogspot.com/2015/06/htb-rate-limiting-not-quite-lining-up.html</a><br /><div><br /></div><div>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.</div><div><br /></div><div>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.</div><div><br /></div><div>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.</div><div><br /></div><div>-Aaron</div></div>
<p style="margin-top: 2.5em; margin-bottom: 1em; border-bottom: 1px solid #000"></p><pre class="k9mail"><hr /><br />Cerowrt-devel mailing list<br />Cerowrt-devel@lists.bufferbloat.net<br /><a href="https://lists.bufferbloat.net/listinfo/cerowrt-devel">https://lists.bufferbloat.net/listinfo/cerowrt-devel</a><br /></pre></blockquote></div><br>
-- <br>
Sent from my Android device with K-9 Mail. Please excuse my brevity.</body></html>