> On 29 Mar, 2015, at 14:16, Sebastian Moeller <moell...@gmx.de> wrote:
Okay, so it looks like you get another 5% without any shaping running. So in summary: - With no shaping at all, the router is still about 10% down compared to downstream line rate. - Upstream is fine *if* unidirectional. The load of servicing downstream traffic hurts upstream badly. - Turning on HTB + fq_codel loses you 5%. - Using ingress filtering via IFB loses you another 5%. - Mangling the Diffserv field loses you yet another 5%. Those 5% penalties add up. People might grudgingly accept a 10% loss of bandwidth to be sure of lower latency, and faster hardware would do better than that, but losing 25% is a bit much. I should be able to run similar tests through my Pentium-MMX within a couple of days, so we can see whether I get similar overhead numbers out of that; I can even try plugging in your shaping settings, since they’re (just) within the line rate of the 100baseTX cards installed in it. I could also compare cake’s throughput to that of HTB + fq_codel; I’ve already seen an improvement with older versions of cake, but I want to see what the newest version gets too. Come to think of it, I should probably try swapping the same cards into a faster machine as well, to see how much they influence the result. >> You see, if we were to use a policer instead of ingress shaping, we’d not >> only be getting IFB and ingress Diffserv mangling out of the way, but HTB as >> well. > > But we still would run HTB for egress I assume, and the current results with > policers Dave hinted at do not seem like good candidates for replacing > shaping… The point of this exercise was to find out whether a theoretical, ideal policer on ingress might - in theory, mind - give a noticeable improvement of efficiency and thus throughput. The existing policers available are indeed pretty unsuitable, as Dave’s tests proved, but there may be a way to do better by adapting AQM techniques to the role. In particular, Codel’s approach of gradually increasing a sparse drop rate seems like it would work better than the “brick wall” imposed by a plain token bucket. Your results suggest that investigating this possibility might still be worthwhile. Whether anything will come of it, I don’t know. - Jonathan Morton _______________________________________________ Cerowrt-devel mailing list Cerowrt-devel@lists.bufferbloat.net https://lists.bufferbloat.net/listinfo/cerowrt-devel
