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From: Eric Dumazet <eric.dumazet@gmail.com>
To: Jesper Dangaard Brouer <jbrouer@redhat.com>
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Cc: codel@lists.bufferbloat.net
Subject: Re: [Codel] hardware multiqueue in fq_codel?
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On Fri, 2013-07-12 at 11:34 +0200, Jesper Dangaard Brouer wrote:

> I also think of "fq_codel" as a good replacement for pfifo_fast.  As
> the 3-PRIO bands in pfifo_fast is replaced with something smarter in
> "fq_codel". (IMHO please don't try to add a prio_fq_codel, just be because
> pfifo_fast had prio bands, people can just enable a prio qdisc if they
> really need it).

Nope. Its really easy for an attacker to flood your fq_codel with say
UDP messages on all available hash slots.

Some people really want the high prio packets to be sent before any
med/low prio packets. Not everybody uses a separate ethernet port for
management and heartbeats.

If we want to replace pfifo_fast as the default qdisc, we want some
integrated qdisc with 3 bands.

I presume something really simple like :

a fifo for band 0 messages
a fq_codel for band 1 messages
a fifo for band 2 messages

Would be more than enough, and this also should use device txqueue len
as the (dynamic) limit, because some existing scripts expect to control
qdisc limit using "ifconfig eth0 txqueuelen 100", not a tc script.