Re: The "tc filter .. police" command does not have parameter "limit"

[Andy Furniss <adf.lists@gmail.com>]

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.

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.