Re: [Xen-devel] [Xen-users] Xen bridging issue.

[johnny Strom <johnny.strom@xxxxxxxxxxxxxxxxx>]

On 09/08/2015 02:45 PM, Wei Liu wrote:
> On Tue, Sep 08, 2015 at 02:33:53PM +0300, johnny Strom wrote:
> > On 09/08/2015 02:12 PM, Wei Liu wrote:
> > > On Tue, Sep 08, 2015 at 02:07:21PM +0300, johnny Strom wrote:
> > > > On 09/08/2015 01:06 PM, Wei Liu wrote:
> > > > > On Tue, Sep 08, 2015 at 12:59:39PM +0300, johnny Strom wrote:
> > > > > > On 09/08/2015 12:13 PM, Wei Liu wrote:
> > > > > > >   xenstore-ls/local/domain/$DOMID/
> > > > > > Here is the output of xenstore-ls only one network card is working.
> > > > > >
> > > > > > xenstore-ls  /local/domain/1
> > > > > [...]
> > > > > >   vif = ""
> > > > > >    0 = ""
> > > > > >     backend = "/local/domain/0/backend/vif/1/0"
> > > > > >     backend-id = "0"
> > > > > >     state = "4"
> > > > > >     handle = "0"
> > > > > >     mac = "00:16:3e:ee:aa:aa"
> > > > > >     multi-queue-num-queues = "17"
> > > > > OK so the number of queues is 17. You probably don't need that many
> > > > > queues.
> > > > >
> > > > > Set module parameter "xenvif_max_queues" of netback to something like 4
> > > > > should work around the problem for you.
> > > > Hello
> > > >
> > > > I tried to set it to 4 in  /etc/modprobe.d/xen_netback.conf
> > > >
> > > > rmmod xen_netback
> > > >
> > > > modprobe -v xen_netback
> > > > insmod
> > > > /lib/modules/3.16.0-4-amd64/kernel/drivers/net/xen-netback/xen-netback.ko
> > > > xenvif_max_queues=4
> > > >
> > > >
> > > >
> > > > But it is still the same issue..
> > > >
> > > > Is xenvif_max_queues supported in Linux kernel 3.16?
> > > >
> > > > modinfo -p xen_netback
> > > >
> > > > separate_tx_rx_irq: (bool)
> > > > rx_drain_timeout_msecs: (uint)
> > > > rx_stall_timeout_msecs: (uint)
> > > > max_queues:Maximum number of queues per virtual interface (uint)
> > > Oh, right, the parameter name should be "max_queues".
> > >
> > > Sorry about that!
> > >
> > > Wei.
> > It's still the same issue:
> >
> > modprobe -v xen_netback
> > insmod
> > /lib/modules/3.16.0-4-amd64/kernel/drivers/net/xen-netback/xen-netback.ko
> > max_queues=4
> If there are the precise steps you took, isn't modprobe -v already
> inserted the module without parameter set? I.e. the later insmod had no
> effect.
Hello again

I am not sure but there might be another issue with the xen_netback 
module in Debian jessie.
I am not able to set the  max_queues options so that it is set at load time.

I have tested with the loop kernel module where it works to set an value 
but doing the same for
the xen_netback driver dose not work:

This works with loop module like this:
options loop max_loop=50

And then doing the same with the xen_netback that dose not work:
options xen_netback max_queues=4

Or is there some other way it should be set in 
/etc/modprobe.d/xen_netback.conf?

Best regards Johnny



> > But what could be reason for this?
> Make sure that parameter is correctly set. You can look at
> /sys/module/xen_netback/parameter/max_queues for the actual number.
>
> You can even just echo a number to that file to set the value on the
> fly.
>
> > Could it be problems with one of the CPUS? since if I boot dom0 with just 14
> > cpu cores then it works....
> No, it can't be related to CPUs.  That's because DomU doesn't exhaust
> resources anymore.
>
> Wei.
>
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