[Cerowrt-devel] [Codel] [Bloat] FQ_Codel lwn draft article review
eric.dumazet at gmail.com
Wed Nov 28 13:51:03 EST 2012
On Wed, 2012-11-28 at 13:37 -0500, Michael Richardson wrote:
> >>>>> "Paul" == Paul E McKenney <paulmck at linux.vnet.ibm.com> writes:
> Paul> You lost me on this one. It looks to me like
> Paul> net/sched/sch_fq_codel.c
> Paul> in fact does hash packets into flows, so FQ-CoDel is
> Paul> stochastic in the
> Paul> the same sense that SFQ is. In particular, FQ-CoDel can hash a thin
> Paul> session into the same flow as a thick session, which really is the
> Paul> birthday effect.
> Silly question from someone who should read more code, but...
> if one is hashing the packet to pick a flow bucket, shouldn't this hash
> occur before any application of address/port translation. ? (NAT)
> (Maybe I've just found out that IPv6 + CoDel will be a killer
Why would it be a killer ?
A NATed flow becomes another flow, with its own hash
A tunnel might have a problem, _if_ the hash would be computed on
elements found on the outer header.
But luckily, we do a complete flow dissection.
(Assuming the default fq_codel classification)
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