Re: [Vserver] packet shaping with vservers

From: Grzegorz Nosek <>
Date: Tue 08 Nov 2005 - 08:08:42 GMT
Message-ID: <>

Hello all,

2005/11/7, Herbert Poetzl <>:
> could you give me some commands to reproduce here?

basically, it amounts to:

tc qdisc del dev eth0 root
tc qdisc add dev eth0 root handle 1: htb default fffe

... still working nicely...

tc class add dev eth0 parent 1: classid 1:fffe htb rate 1Gbit ceil 1Gbit

networking goes south here, I also tried with reduced quantum (both
here and using r2q in qdisc definition) and burst size. The specified
rate and ceil don't seem to matter.

It is perfectly reproducible on this machine. However, I cannot
reproduce it on another one... I'm gonna grow grey hair soon ;) If you
want me to do some testing, I'll be happy to.

> > - default class on eth0 set to htb (rate 1Gbit, so it's not true
> > bandwith choking) mysql connections seem to take forever to establish
> > (lots of unauthenticated user connections as they are too throttled to
> > even log in and time out eventually)
> about what kind of delays are we talking here?

While testing with ping -f w/o QoS, the reply is instantaneous [sp?].
If I set up shaping as above (on eth0), it gets slowly backlogged, at
a rate of roughly 1pps. The rate is not linear, rather burst-like
(say, 10 seconds OK, after 10 more seconds 10 packets get backlogged
almost at once [dots in ping -f], after 10s more the backlog jumps to
20 etc). The packets are not dropped because if I delete the root
qdisc, the backlog is gone with no lost packets.

With MySQL the story is essentially the same. Without QoS all
connections are served immediately, when I enable HTB, mysql -e "show
processlist" shows loads of unauthenticated connections (so at least
the TCP handshake packets reach MySQL).

> local packets (host-guest, guest-guest) will not pass
> through ethX, they will use lo ...

That's what the routing table and common sense says too.

> > Have you got any ideas/suggestions? Is this a known issue?
> nope, not known yet ...

It's a shame :( I need to rate limit eth0 but I cannot allow such
latencies on eth0... if you come up with any idea, please let me know
ASAP. Will you be available on IRC today?
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Received on Tue Nov 8 08:09:01 2005

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