freebsd stable - Sep 2017 - 11.1 running on HyperV hn interface hangs

On Fri, Sep 29, 2017 at 12:36 PM, Paul Koch <paul.koch at akips.com>
wrote:
> On Thu, 14 Sep 2017 09:54:56 +0800
> Sepherosa Ziehau <sephe at freebsd.org> wrote:
>
>> If you have any updates on this, please let me know.  There is still
>> time for 10.4.
>
> We are still playing around with this in the lab...
>
> Running similar setup as the customer
>  Microsoft Windows Server 2012 R2 Datacentre (6.3.9600) Revision 16384
>  Hyper-V 2012
>
> Two VM guests
>  - 11.0-RELEASE
>  - 11.1-p1
>
> We can not get the Hyper-V hn interface to lock up like the customer can
> though.
>
> We can get the VMs to hang/stall regularly if the guests run ntpd - approx
> every 15 mins, but no real obvious pattern to it.  Disabling ntpd fixes it.
Hmm, by ntpd I think you mean ntp client?  You will have to disable
timesync if you run ntp client:
sysctl hw.hvtimesync.sample_thresh=-1
sysctl hw.hvtimesync.ignore_sync=1

They interfere w/ each other.

Or do you mean the network hanging triggered by "RXBUF ack failed"?

Thanks,
sephe


-- 
Tomorrow Will Never Die

On Fri, 29 Sep 2017 13:31:22 +0800
Sepherosa Ziehau <sephe at freebsd.org> wrote:
> On Fri, Sep 29, 2017 at 12:36 PM, Paul Koch <paul.koch at akips.com>
wrote:
> > On Thu, 14 Sep 2017 09:54:56 +0800
> > Sepherosa Ziehau <sephe at freebsd.org> wrote:
> >  
> >> If you have any updates on this, please let me know.  There is
still
> >> time for 10.4.  
> >
> > We are still playing around with this in the lab...
> >
> > Running similar setup as the customer
> >  Microsoft Windows Server 2012 R2 Datacentre (6.3.9600) Revision 16384
> >  Hyper-V 2012
> >
> > Two VM guests
> >  - 11.0-RELEASE
> >  - 11.1-p1
> >
> > We can not get the Hyper-V hn interface to lock up like the customer
can
> > though.
> >
> > We can get the VMs to hang/stall regularly if the guests run ntpd -
approx
> > every 15 mins, but no real obvious pattern to it.  Disabling ntpd
fixes
> > it.  
> 
> Hmm, by ntpd I think you mean ntp client?  You will have to disable
> timesync if you run ntp client:
> sysctl hw.hvtimesync.sample_thresh=-1
> sysctl hw.hvtimesync.ignore_sync=1
> 
> They interfere w/ each other.
> 
> Or do you mean the network hanging triggered by "RXBUF ack
failed"?
> 
> Thanks,
> sephe
Yes, ntp client running on the VM guest.  After finding it was unstable, we
concluded that there must be some type of interference.  Best that we
automatically force ntp off when our software detects it is running in
Hyper-V.

We haven't been able to trigger the hn to hang like our customer can with
the
RXBUF problem though.  Different underlying hardware probably.

	Paul.
-- 
Paul Koch | Founder | CEO
AKIPS Network Monitor | akips.com
Brisbane, Australia

> Hmm, by ntpd I think you mean ntp client?  You will have to disable
> timesync if you run ntp client:
> sysctl hw.hvtimesync.sample_thresh=-1
> sysctl hw.hvtimesync.ignore_sync=1
>
> They interfere w/ each other.
Oh! Does this apply to machines in Azure Hyper-V as well as on standalone
installations ? I wasn't aware of this, and have ntp on as standard (which
I wil now turn off pending a reply to this email, as sods law says that now
I am aware of it then I will get lockups over the weekend) :-)

-pete.