Re: [Xen-users] domU with two eth but only one is active

[SZABO Zsolt <szazs@xxxxxxxxx>]

On Sat, 18 Jul 2015, Ian Campbell wrote:
> On Sat, 2015-07-18 at 11:07 +0200, SZABO Zsolt wrote:
> > [...]
> > I have also checked dmesg in the guest:
> > # dmesg |grep -i net
> > [    0.033297] Initializing cgroup subsys net_cls
> > [    0.033330] Initializing cgroup subsys net_prio
> > [    0.118117] NET: Registered protocol family 16
> > [    0.208776] NET: Registered protocol family 2
> > [    0.212141] NET: Registered protocol family 1
> > [    0.301223] audit: initializing netlink subsys (disabled)
> > [    1.376536] NET: Registered protocol family 10
> > [    1.377181] NET: Registered protocol family 17
> > [    1.472973] xen_netfront: Initialising Xen virtual ethernet driver
> > [    1.601085] xen_netfront: can't alloc rx grant refs
> This is strange, and I would bet related to your problem.
>
> > [    1.601105] net eth1: only created 16 queues
> and this is maybe related too.
>
> I'm afraid I've run out of time to investigate for the weekend, but I'll
> see what I can figure out next week.
>
> In the meantime off the top of my head in addition to googling those
> messages it might be worth investigating options for extending the
> number of grant entries which a guest is allowed to use and perhaps
> whether multiqueue networking can be disabled (therefore reducing the
> need for grant entries).
Hmm.. I have no idea how to do that... :-)


> > Ok, I have another linux domU but with wheezy. Originally, only eth0 was
> > configured, but now I have also tried to add eth1 similarly as to
> > the jessie domU and it works...
> > The dmesg of this domU is shorter:
> > # dmesg |grep net
> > [    0.004000] Initializing cgroup subsys net_cls
> > [    0.004000] Initializing cgroup subsys net_prio
> > [    0.134838] audit: initializing netlink subsys (disabled)
> > [    1.340978] xen_netfront: Initialising Xen virtual ethernet driver
> >
> > Maybe the jessie upgrade missed some feature of the later upgraded dom0?
> > Or it is about some kind of other conflict...?
> I think a new feature of the Jessie kernel(s) is running up against some
> resource limit when two NICs are used.
And one more report, with some summary[1-3]:

[1]Finally I have also tried to start the jessie domU with kernel 3.2.0:
$ uname -a
Linux linserver 3.2.0-4-amd64 #1 SMP Debian 3.2.68-1+deb7u2 x86_64 GNU/Linux
(still from wheezy)
... and it WORKS!

# dmesg |grep -i 'net\|eth'
[    0.040200] Initializing cgroup subsys net_cls
[    0.089581] NET: Registered protocol family 16
[    0.202444] NET: Registered protocol family 2
[    0.215637] NET: Registered protocol family 1
[    0.287638] audit: initializing netlink socket (disabled)
[    1.366956] NET: Registered protocol family 10
[    1.367898] NET: Registered protocol family 17
[    1.368263] Initializing network drop monitor service
[    1.435843] Initialising Xen virtual ethernet driver.
[   18.854461] FS-Cache: Netfs 'nfs' registered for caching
[   25.868039] eth0: no IPv6 routers present
[   27.740048] eth1: no IPv6 routers present

[2]So, the TWO vif in a wheezy domU with linux-3.16.0 work too;
# uname -a
Linux wheezy 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt11-1 (2015-05-24) x86_64 
GNU/Linux
(the part of dmesg related to net|eth can be seen above)

[3]But the 2nd vif in a jessie domU with linux-3.16.0 does NOT,
and it is possibly related to the dmesg lines
* xen_netfront: can't alloc rx grant refs
* net eth1: only created 16 queues

Now, I run the jessie+3.2.0 domU and I will see how stable it is...

--
Zsolt

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