From: Bill Fink <billfink@mindspring•com>
To: Jarek Poplawski <jarkao2@gmail•com>
Cc: Rick Jones <rick.jones2@hp•com>,
Steven Brudenell <steven.brudenell@gmail•com>,
netdev@vger•kernel.org
Subject: Re: tbf/htb qdisc limitations
Date: Thu, 14 Oct 2010 03:13:54 -0400 [thread overview]
Message-ID: <20101014031354.e172d737.billfink@mindspring.com> (raw)
In-Reply-To: <20101014064404.GA6219@ff.dom.local>
On Thu, 14 Oct, Jarek Poplawski wrote:
> On Wed, Oct 13, 2010 at 11:36:53PM -0400, Bill Fink wrote:
> > On Wed, 13 Oct 2010, Jarek Poplawski wrote:
> >
> > > On Tue, Oct 12, 2010 at 03:17:18PM -0700, Rick Jones wrote:
> > > >>> my burst problem is the only semi-legitimate motivation i can think
> > > >>> of. the only other possible motivations i can imagine are setting
> > > >>> "limit" to buffer more than 4GB of packets and setting "rate" to
> > > >>> something more than 32 gigabit; both of these seem kind of dubious. is
> > > >>> there something else you had in mind?
> > > >>
> > > >>
> > > >> No, mainly 10 gigabit rates and additionally 64-bit stats.
> > > >
> > > > Any issue for bonded 10 GbE interfaces? Now that the IEEE have ratified
> > > > (June) how far out are 40 GbE interfaces? Or 100 GbE for that matter.
> > >
> > > Alas packet schedulers using rate tables are still around 1G. Above 2G
> > > they get less and less accurate, so hfsc is recommended.
> >
> > I was just trying to do an 8 Gbps rate limit on a 10-GigE path,
> > and couldn't get it to work with either htb or tbf. Are you
> > saying this currently isn't possible?
>
> Let's start from reminding that no precise packet scheduling should be
> expected with gso/tso etc. turned on. I don't know current hardware
> limits for such a non-gso traffic, but for 8 Gbit rate htb or tbf
> would definitely have wrong rate tables (overflowed values) for packet
> sizes below 1500 bytes.
TSO/GSO was disabled and was using 9000-byte jumbo frames
(and specified mtu 9000 to tc command).
Here was one attempt I made using tbf:
tc qdisc add dev eth2 root handle 1: prio
tc qdisc add dev eth2 parent 1:1 handle 10: tbf rate 8900mbit buffer 1112500 limit 10000 mtu 9000
tc filter add dev eth2 protocol ip parent 1: prio 1 u32 match ip dst 192.168.1.23 flowid 10:1
I tried many variations of the above, all without success.
> > Or are you saying to use
> > this hfsc mechanism, which there doesn't seem to be a man page
> > for?
>
> There was a try:
> http://lists.openwall.net/netdev/2009/02/26/138
Thanks for the pointer. I will check it out later in detail,
but I'm already having difficulty with deciding if I have the
tc commands right for tbf and htb, and hfsc looks even more
involved.
-Bill
next prev parent reply other threads:[~2010-10-14 7:13 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-08 20:58 tbf/htb qdisc limitations Steven Brudenell
2010-10-10 11:23 ` Jarek Poplawski
2010-10-11 22:27 ` Steven Brudenell
2010-10-12 10:10 ` Jarek Poplawski
2010-10-12 19:31 ` Steven Brudenell
2010-10-12 21:59 ` Jarek Poplawski
2010-10-12 22:17 ` Rick Jones
2010-10-13 6:26 ` Jarek Poplawski
2010-10-14 3:36 ` Bill Fink
2010-10-14 4:01 ` Eric Dumazet
2010-10-14 6:34 ` Bill Fink
2010-10-14 6:44 ` Jarek Poplawski
2010-10-14 7:13 ` Bill Fink [this message]
2010-10-14 8:09 ` Jarek Poplawski
2010-10-14 8:50 ` Jarek Poplawski
2010-10-15 6:37 ` Bill Fink
2010-10-15 6:44 ` Eric Dumazet
2010-10-15 21:37 ` Bill Fink
2010-10-15 22:05 ` Jarek Poplawski
2010-10-16 4:51 ` Bill Fink
2010-10-16 20:58 ` Jarek Poplawski
2010-10-17 1:24 ` Bill Fink
2010-10-17 20:36 ` Jarek Poplawski
2010-10-19 7:37 ` Bill Fink
2010-10-20 11:06 ` Jarek Poplawski
2010-10-27 4:51 ` Bill Fink
2010-10-27 9:48 ` Jarek Poplawski
2010-10-15 8:18 ` Jarek Poplawski
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