[Cerowrt-devel] archer c7 v2, policing, hostapd, test openwrt build

David Lang david at lang.hm
Sun Mar 22 21:45:51 EDT 2015

On Mon, 23 Mar 2015, Jonathan Morton wrote:

>> On 23 Mar, 2015, at 02:24, Dave Taht <dave.taht at gmail.com> wrote:
>> I have long maintained it was possible to build a better fq_codel-like
>> policer without doing htb rate shaping, ("bobbie"), and I am tempted
>> to give it a go in the coming months.
> I have a hazy picture in my mind, now, of how it could be made to work.
> A policer doesn’t actually maintain a queue, but it is possible to calculate when the currently-arriving packet would be scheduled for sending if a shaped FIFO was present, in much the same way that cake actually performs such scheduling at the head of a real queue.  The difference between that time and the current time is a virtual sojourn time which can be fed into the Codel algorithm.  Then, when Codel says to drop a packet, you do so.
> Because there’s no queue management, timer interrupts nor flow segregation, the overhead should be significantly lower than an actual queue.  And there’s a reasonable hope that involving Codel will give better results than either a brick-wall or a token bucket.

are we running into performance issues with fq_codel? I thought all the problems 
were with HTB or ingress shaping.

David Lang

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