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Re: xennetback_ifstart: no mcl_pages crashes XEN2-dom0


Again my dom0 crashed this night.
The dom0 showed the same message as few weeks ago:

Manuel Bouyer wrote:
>> May 30 10:07:48 pless /netbsd: xennetback_ifstart: no mcl_pages
>> And the last two lines repeat 1000+ times....
>> What are those mcl pages?
> Memory that dom0 reclaims from the hypervisor to remplace pages that
> we gave to the remote domains when sending packets

Ok, I think I got it.

>> I read on the list something about XEN-DOM0 needing 32MB for itself.
>> (Date of posting: 4/15/2005 6pm from Manuel Bouyer) Does it mean that I
>> have to increase my 2MB of free memory to 32? That's actually what I'd
>> try next...
> I strongly suspect that there's not enough free ram for the hypervisor.

Should the free ram be under dom0? As I understand XEN, the hypervisor
ist running in dom0, right? The dom0 has 64MB of its own memory. Since
it isn't doing anything else but providing XEN, I thought it would be
enough. I could spare some more MB (up to 90) if it is necessary. Is it?

> I think the 32MB is not counted as part of "xm info", but it's something
> that can't ever be allocated to domains anyway, it's internal to the
> hypervisor.

So nobody noticed problems having 2MB free in "xm info"? The free ram
has no meaning but showing a waste of memory?

> You'll also need some free pages for the communications between
> domains.

There is a lot of communication between the domUs. I resized the
NMBCLUSTERS to 2048. Should I increase it even more?

>> Another idea which will be quite time consuming and I would like to
>> Is it worth it to update to a newer Beta-version of NetBSD4 with a newer
>> Kernel?
> I don't think it will help.

Ok, that will save me some time. Should I maybe upgrade to XEN 3? Did it
turn out to be more stable? My dom0 is running NetBSD Beta anyway so a
switch won't cause many changes.

Thanks for any help.

Damian Lubosch

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