Re: dynamically set bandwidth limits of a virtual interface

[Wei Liu <Wei.Liu2@citrix.com>]

On Sun, 2012-12-30 at 12:08 +0000, Rohit Damkondwar wrote:


>         TBH I'm not sure about this either. Again, comparisons and
>         analysis of
>         bottleneck would be helpful.
>         
>         >
>         > I have seen  function "set_qos_algorithm_type" and
>         paramaters
>         > (qos/algorithm type,qos/algorithm params, qos/supported
>         algorithms) in
>         > vif class. Would they be useful ? Are they available only
>         for XEN
>         > Enterprise ?
>         >
>         
>         
>         Do you see those in libxen source code? I don't think they are
>         in use
>         now.
> I didn't know that. The when which library should I look into? I could
> find vif class in libxen folder. So I thought it should be used. I
> read that xl is not matured enough in xen 4.1.3. So which library
> should I look into? Please help. 

There is considerable amount of work to be done.

Tool stack is relatively easy. You can try adding config options to
whatever tool stack you're using. You need to parse the config option
(which is easy, because every tool stack has parser), then write the
option to xenstore so that guest can pick it up.

To modify the kernel is a bit harder. Download kernel package, look for
netback.c and friends, whose location varies depending the kernel you're
using. Grep for 'rate' so that you can have a look at how tx rate limit
is implemented.

The last bit is to upsteam your changes. Please post your changes to
Xen-devel to see if it is suitable for upstreaming. Of course this is
not mandatory. By upstreaming your changes you can 1) relieve your
maintenance burden, 2) benefit others.


Wei.