Xen devel - Jan 2006 - RE: xen 3 dom0 eats memory - ME TOO

I have a similar situation on two machines running xen3 (xen-3.0-testing
20051228). After a short time (days) dom0 fills up with memory and
eventually kills the watchdog process (which in turn reboots the machine
as I use softdog with the nowayout module option, for exactly this
reason).

I am using bridging, not nat, if that makes any difference.

I''ll add free memory to mrtg and see what that uncovers...

James
> -----Original Message-----
> From: xen-devel-bounces@lists.xensource.com [mailto:xen-devel-
> bounces@lists.xensource.com] On Behalf Of Patrick Scharrenberg
> Sent: Thursday, 5 January 2006 00:43
> To: Xen-devel@lists.xensource.com
> Subject: [Xen-devel] xen 3 dom0 eats memory
> 
> Hi!
> 
> Since my upgrade from xen 2-testing  to xen 3-testing I have the
problem
> that domain0 consumes more and more memory on domU networktraffic.
> It is about 50 bytes per packet that gets lost.
> 
> I reproduced the bug on another machine.
> 
> In normal bridged setup all works fine.
> 
> I changed the setup in the following way:
> - added an ip address to the bridge (in another subnet (B))
> - changed domU ip address to a net B address
> - added masquerading for eth0 in the postrouting-chain in dom0
> 
> After that I pinged a host outside this machine.
> 
> Sending and receiving 100.000 pakets results to a
> dom0-memory-consumption increasement of about 5 MB!
> 
> I have to restart this machine once a day for not running out of
memory.
> 
> What can I do?
> 
> Patrick
> 
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On 4 Jan 2006, at 23:15, James Harper wrote:
> I have a similar situation on two machines running xen3 
> (xen-3.0-testing
> 20051228). After a short time (days) dom0 fills up with memory and
> eventually kills the watchdog process (which in turn reboots the 
> machine
> as I use softdog with the nowayout module option, for exactly this
> reason).
>
> I am using bridging, not nat, if that makes any difference.
>
> I''ll add free memory to mrtg and see what that uncovers...
Looks like somethign allocates lots of 64-byte buffers and never frees 
them. I don''t currently know what is doing those allocations. It might 
be worth adding tracing to kmalloc().

  -- Keir


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Keir Fraser schrieb:
>> I''ll add free memory to mrtg and see what that uncovers...
>
> Looks like somethign allocates lots of 64-byte buffers and never frees
> them. I don''t currently know what is doing those allocations. It
might
> be worth adding tracing to kmalloc().
I  changed my configuration in the following way and now no memory gets
lost.

I leave the physical eth0 as it is when the machine boots, create a
bridge which holds all vif''s of the domUs.
So I have no vif for dom0 and use the physical ethernet interface directly.
Turn on masquerading for eth0 like I did before.

Now it works.

It seems that the "virtualisazion" of the ethernet interface is
responsible for the troubles.


Patrick

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