Date: Mon, 25 Jul 2016 16:43:43 +0200 From: Roger Pau =?iso-8859-1?Q?Monn=E9?= <roger.pau@citrix.com> To: Karl Pielorz <kpielorz_lst@tdx.co.uk> Cc: "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: <20160725144314.yhggviqhsqzgux2w@mac> In-Reply-To: <FA258C50EA60D4DE44D9289C@[10.12.30.106]> References: <41E487BC91654544B2B8F31096F2D9D4D1514D1D8E@ex1> <20160714103016.4hgfzsjgkkgtkkgg@mac> <41E487BC91654544B2B8F31096F2D9D4D1514D1E88@ex1> <20160720093111.mpmp27wol7j3ge3d@mac> <41E487BC91654544B2B8F31096F2D9D4D1516490E9@ex1> <20160722115542.dopzb63dgkilqall@mac> <FA258C50EA60D4DE44D9289C@[10.12.30.106]>
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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?
Roger.
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