Re: 'Live' Migrate messes up NTP on FreeBSD domU - any suggestions?
--On 22 July 2016 13:55 +0200 Roger Pau Monné 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 don't have a crashdump (failed). I did get a backtrace, for what it's
worth.
I'm running the test again now (in case it panics again - I'll try harder
to get a dump just in case).
-Karl
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Re: 'Live' Migrate messes up NTP on FreeBSD domU - any suggestions?
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 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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Re: 'Live' Migrate messes up NTP on FreeBSD domU - any suggestions?
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 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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