On Sun, Aug 3, 2014 at 6:06 PM, Andy Furniss <adf.lists@xxxxxxxxx> wrote: > Fengyu Gao wrote: >> >> Hi, >> >> I have a question about the "tc filter ... police" command. This >> command is similar to the token bucket filter. Under Linux, ingress >> traffic can be redirected to an imq or ifb, then you can apply a tbf >> there. >> >> However, tbf has an important parameter "limit", which is the size >> of the buffer for waiting packets, and it is different from the >> "burst" parameter. In the "tc filter ... police" command, there does >> not seem to be a "limit" parameter, and there seems to be no document >> or discussions about it. Digging into the Linux kernel might be a >> bit difficult for me. So my question is what is the buffer size in >> this case? > > > Policers do not buffer and as a result can be a bit aggressive. +1 http://www.bufferbloat.net/projects/cerowrt/wiki/Wondershaper_Must_Die > > IIRC the burst parameter is like a virtual buffer but policers > never hold the packets - just pass or drop. > > Personally I would rather shape but then you have to consider latency > added by buffering. To avoid this you may need to classify traffic to > give latency sensitive priority. > > fq_codel could be worth investigating as a single qdisc alternative to a > policer. What I am doing with reasonable success is using act_mirred, with an inbound ifb device, + htb + fq_codel A simple example here: http://wiki.gentoo.org/wiki/Traffic_shaping (note that the fq_codel target and interval should be increased to account for an MTU's worth of packets at below 3mbit) A more complex example can be had in various qos scripts, the sqm scripts in cerowrt also do inbound diffserv squashing and a few other tricks. https://github.com/dtaht/ceropackages-3.10/tree/master/net/sqm-scripts/files/usr/lib/sqm While somewhat openwrt specific by default they can be easily used with any modern linux kernel. > > -- > To unsubscribe from this list: send the line "unsubscribe lartc" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Dave Täht NSFW: https://w2.eff.org/Censorship/Internet_censorship_bills/russell_0296_indecent.article -- To unsubscribe from this list: send the line "unsubscribe lartc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
