Re: [Xen-users] Maximum VIFs?

[Tim Post <tim.post@xxxxxxxxxxxxxxx>]

On Fri, 2006-12-08 at 15:08 -0500, Carb, Brian A wrote:

> Is there a maximum number of vifs that can be attached to a single xen
> bridge?

I've yet to reach one. I think you'd exceed the heap size (and max # of
default guests - being around 100 or so) before you overloaded the
bridge assuming its porting a gig-e nic. I've never had more than 40 or
50 vifs tied to a single bridge.

Looking at your company name I can see why you're asking :) 

I'm sure there is some sort of limit, but its so high you'd never reach
it with any kind of sane configuration. Someone else may be able to
comment on what it is. I think a few limits come into play, a sanity
limit on the bridge (how many will it allow) and available ram to store
structures for each vif on dom-0. 

In case I misunderstood your question, if your looking for how many
vif's can be attached to a guest, its currently 3. I believe this is due
to the size of the structures that are needed to create each ethernet
device in a guest (approximately 1 page per). 

I don't know if this is one page on dom-0 for the bridge and one page in
the guest .. but ether way this is going to be influenced by how much
ram is available to dom-0.

Even if it was a full page per nic that the bridge used on dom-0, ( [xen
pagesize] * # of vifs ) * 2 should let you adequately size dom-0. 

Does anyone know if its a full page consumed on dom-0 + a full page in
each guest per nic?

Best,
Tim

> brian carb
> unisys corporation - malvern, pa
> brian.carb@xxxxxxxxxx
> 
> 
> _______________________________________________
> Xen-users mailing list
> Xen-users@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-users


_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users