[Xen-users] Re: [Xen-devel] kernel oops/IRQ exception when networking between many domUs

[Birger Tödtmann <btoedtmann@xxxxxxxxxxxxxx>]

Am Montag, den 06.06.2005, 10:26 +0100 schrieb Keir Fraser:
[...]
> > somewhere around the magic 128 (NR_IRQS problem in 2.0.x!) when the
> > crash happens - could this hint to something?
> 
> The crashes you see with free_mfn removed will be impossible to debug 
> -- things are very screwed by that point. Even the crash within 
> free_mfn might be far removed from the cause of the crash, if it's due 
> to memory corruption.
> 
> It's perhaps worth investigating what critical limit you might be 
> hitting, and what resource it is that's limited. e.g., can you can 
> create a few vifs, but connected together by some very large number of 
> bridges (daisy chained together)? Or can you create a large number of 
> vifs if they are connected together by just one bridge?

This is getting really weird - as I found out I'll enounter problems
with far fewer vifs/bridges that suspected.  I just fired up a network
with 7 nodes, all with four interfaces each connected to the same four
bridge interfaces.  The nodes can ping through the network, however
after a short time, the system (dom0) crashes as well.  This time, it
dies in net_rx_action() at a slightly different place:

[...]
 [<c02b6e15>] kfree_skbmem+0x12/0x29
 [<c02b6ed1>] __kfree_skb+0xa5/0x13f
 [<c028c9b3>] net_rx_action+0x23d/0x4df
[...]

Funnily, I cannot reproduce this with 5 nodes (domUs) running.  I'm a
bit unsure where to go from here...  Maybe I should try a different
machine for further testing.


Regards
-- 
Birger Tödtmann
Technik der Rechnernetze, Institut für Experimentelle Mathematik
Universität Duisburg-Essen, Campus Essen email:btoedtmann@xxxxxxxxxxxxxx
skype:birger.toedtmann pgp:0x6FB166C9

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