From: Stephen Hemminger <shemminger@vyatta•com>
To: Eric Dumazet <eric.dumazet@gmail•com>
Cc: David Miller <davem@davemloft•net>,
Dave Taht <dave.taht@gmail•com>,
"John A. Sullivan III" <jsullivan@opensourcedevel•com>,
netdev@vger•kernel.org
Subject: Re: [PATCH net-next] netem: fix classful handling
Date: Wed, 28 Dec 2011 22:17:31 -0800 [thread overview]
Message-ID: <20111228221731.4d4954a9@s6510.linuxnetplumber.net> (raw)
In-Reply-To: <1325132760.2607.15.camel@edumazet-laptop>
On Thu, 29 Dec 2011 05:26:00 +0100
Eric Dumazet <eric.dumazet@gmail•com> wrote:
> Commit 10f6dfcfde (Revert "sch_netem: Remove classful functionality")
> reintroduced classful functionality to netem, but broke basic netem
> behavior :
>
> netem uses an t(ime)fifo queue, and store timestamps in skb->cb[]
>
> If qdisc is changed, time constraints are not respected and other qdisc
> can destroy skb->cb[] and block netem at dequeue time.
>
> Fix this by always using internal tfifo, and optionally attach a child
> qdisc to netem.
>
> Example of use :
>
> DEV=eth3
> tc qdisc del dev $DEV root
> tc qdisc add dev $DEV root handle 30: est 1sec 8sec netem delay 20ms 10ms
> tc qdisc add dev $DEV parent 30:0 sfq
Does it work with TBF which is a more useful option?
Also, the whole tfifo idea is only to support the wierd idea that
if doing random delay that packets should get reordered based on the
results of the random value; it was an behavior some users wanted
because that is what NISTnet did.
next prev parent reply other threads:[~2011-12-29 6:17 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-18 5:12 netem and hierarchical ingress traffic shaping John A. Sullivan III
2011-12-18 19:55 ` Stephen Hemminger
2011-12-19 16:53 ` John A. Sullivan III
2011-12-23 17:33 ` Eric Dumazet
2011-12-23 17:39 ` Eric Dumazet
2011-12-23 17:54 ` Dave Taht
2011-12-23 18:28 ` Eric Dumazet
2011-12-23 18:54 ` Dave Taht
2011-12-23 19:07 ` Stephen Hemminger
2011-12-23 19:21 ` Eric Dumazet
2011-12-29 4:26 ` [PATCH net-next] netem: fix classful handling Eric Dumazet
2011-12-29 6:17 ` Stephen Hemminger [this message]
2011-12-29 9:12 ` Eric Dumazet
2011-12-29 16:52 ` Hagen Paul Pfeifer
2011-12-29 17:15 ` Eric Dumazet
2011-12-29 17:43 ` Hagen Paul Pfeifer
2011-12-29 18:10 ` Eric Dumazet
2011-12-29 18:25 ` Hagen Paul Pfeifer
2011-12-29 18:31 ` Stephen Hemminger
2011-12-29 18:36 ` Eric Dumazet
2011-12-30 22:12 ` David Miller
2011-12-23 19:36 ` netem and hierarchical ingress traffic shaping David Miller
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