Re: [Cake] [RFC PATCH 2/3] Add cake related includes and source files

[Dave Taht <dave@taht.net>]

Jonathan Morton <chromatix99@gmail.com> writes:

> On 17/11/17 21:52, Dave Taht wrote:
>> Actually using **to_free sanely (here, in qdisc_reduce_backlog, etc)
>> would be good. I like very much how fq_codel does bulk dropping now.
>>
>> I think, but am unsure, that the whole heap concept would just "go",
>> in that case.
>
> I don't see how.

My principal point was that the bulk_drop facility now in fq_codel was
very cpu efficient. I'm willing to keep this, but I'd like to see it
benchmarked under the same udp_flood scenarios as what prompted that
change to fq_codel - Say, a 1Gbit flood into a 10 or a 100Mbit shaped
connection.


> The max-heap is not used to keep track of packets to drop, but which queue is
> the longest.  If a single flow goes completely crazy, that allows dropping a lot
> of packets from *that* queue without having to search over the others every
> time.  At the same time, if the queues are more evenly filled, it still allows
> the longest queues to be trimmed without overly penalising whichever queue
> happened to get caught at the wrong moment.
>
> In cases where several packets need to be dropped to maintain the backlog limit,
> those packets already end up on 'to_free' correctly. Isn't that how it's
> supposed to work?