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Re: [Xen-devel] Linux Traffic Shaping broken in 3.0.3rc1 ?

Keir Fraser wrote:
> On 8/10/06 5:17 pm, "Matt Ayres" <matta@xxxxxxxxxxxx> wrote:
>> with Xen 3.0.2 i used tc to limit the outgoing traffic rate and it
>> worked very well and accurate with the HTB class:
>> Why not just use Xen's own rate limiting system that works directly on
>> the vif device line?
> Yes, that's the best way. It's odd that TC behaviour has changed though.

AFAIK Xens rate limiting feature is limited to outgoing traffic and i
implement a rather complex (complex at least with tc) scenario:

- each domain will get a guaranteed minimum bandwidth
- if one domain is not using all of the guaranteed bandwidth, the not
  used bandwidth can be reused by other domains in addition to the
  guaranteed bandwidth they own
- in- and outcoming traffic will be limited

That is perfectly possible with tc and the HTB queue, but imho not with 
Xens rate limiting feature.

The other reason was that in my experience rate limiting in 3.0.2 was
buggy and leaving undestroyable zombie domains.

BTW a quick test on 3.0.3rc2 showed the following behaviour of Xen rate
limiting on my host:
vif = [ 'rate=1MB/s' ]

xendom0:~ # xm shutdown xendom2 # rate limited domain
[... wait until xendom2 shutdown finished ...]

xendom0:~ # xm list
Error: Device 0 not connected
Usage: xm list [options] [Domain, ...]

List information about all/some domains.
  -l, --long                     Output all VM details in SXP
  --label                        Include security labels

However, besides my personal problem with my setup that is not working
anymore i think tc is a important feature in QoS environments and should
work as solid on a Xen kernel as it runs on a legacy Linux kernel.


-- Timo Benk - B1 Systems GmbH (http://www.b1-systems.de) 
Jabber ID: fry@xxxxxxxxxx - ICQ ID: #241877854 
PGP Public Key: http://m28s01.vlinux.de/b1_gpg_key.asc

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