Date: Mon, 25 Jul 2016 16:37:14 +0100 From: Wei Liu <wei.liu2@citrix.com> To: Roger Pau =?iso-8859-1?Q?Monn=E9?= <roger.pau@citrix.com> Cc: Karl Pielorz <kpielorz_lst@tdx.co.uk>, "Hoyer-Reuther, Christian" <Christian.Hoyer-Reuther@cac-chem.de>, <freebsd-xen@freebsd.org>, <wei.liu2@citrix.com> Subject: Re: 'Live' Migrate messes up NTP on FreeBSD domU - any suggestions? Message-ID: <20160725153714.GW27082@citrix.com> In-Reply-To: <20160725144314.yhggviqhsqzgux2w@mac> References: <41E487BC91654544B2B8F31096F2D9D4D1514D1D8E@ex1> <20160714103016.4hgfzsjgkkgtkkgg@mac> <41E487BC91654544B2B8F31096F2D9D4D1514D1E88@ex1> <20160720093111.mpmp27wol7j3ge3d@mac> <41E487BC91654544B2B8F31096F2D9D4D1516490E9@ex1> <20160722115542.dopzb63dgkilqall@mac> <FA258C50EA60D4DE44D9289C@[10.12.30.106]> <20160725144314.yhggviqhsqzgux2w@mac>
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On Mon, Jul 25, 2016 at 04:43:43PM +0200, Roger Pau Monné wrote:
> Adding Wei to the Cc list since he added the multiqueue functionality.
>
> On Mon, Jul 25, 2016 at 02:59:02PM +0100, Karl Pielorz wrote:
> >
> > --On 22 July 2016 13:55 +0200 Roger Pau Monné <roger.pau@citrix.com> wrote:
> >
> > > In my environment I've migrated a FreeBSD VM with 2 cpus for > 100
> > > consecutive times without seeing any issues (or freezes), although this
> > > was with OSS Xen and without xe-guest-utilities. Karl, have you tested
> > > HEAD recently?
> >
> > Ok, I have tested this with r303286 - it seems to work OK. The hosts gain no
> > time that I can see while migrating, and NTP stays happy.
> >
> > I did get a panic after about 40 migrations - but that seems to be some
> > network issue or something...
> >
> > ('panic called with 0 available queues / dbt_trace_self_wrapper / vpanic /
> > kassert_panic / xn_txq_mq_start / ether_output / udp_send / sosend_dgram /
> > kern_sendit / sendit / sys_sendto / amd64_syscall / Xfast_syscall)
>
> I haven't been able to reproduce this, but I think it's possible that if you
> migrate an active netfront xn_txq_mq_start might be called during the
> migration, just in the middle of the setup_device reconfiguation (while
> info->num_queues is 0).
>
> Wei, I think netif_disconnect_backend should set IFF_DRV_OACTIVE in order to
> notify the net subsystem that the queues are full, so no further calls to
> xn_txq_mq_start happen until the resume has finished, do you agree?
>
Perhaps clear IFF_DRV_RUNNING and only set it when the device is ready?
Looking at the manpage is seems more appropriate to me semantically.
Wei.
> Roger.
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