Re: [Xen-devel] [xen-unstable test] 128240: regressions - FAIL

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On 10/01/2018 04:17 PM, Wei Liu wrote:
> On Mon, Oct 01, 2018 at 09:10:25AM -0600, Jan Beulich wrote:
>>>>> On 01.10.18 at 16:33, <wei.liu2@xxxxxxxxxx> wrote:
>>> On Mon, Oct 01, 2018 at 03:04:02AM -0600, Jan Beulich wrote:
>>>>>>> On 30.09.18 at 23:59, <osstest-admin@xxxxxxxxxxxxxx> wrote:
>>>>> flight 128240 xen-unstable real [real]
>>>>> http://logs.test-lab.xenproject.org/osstest/logs/128240/ 
>>>>>
>>>>> Regressions :-(
>>>>>
>>>>> Tests which did not succeed and are blocking,
>>>>> including tests which could not be run:
>>>>>  test-amd64-amd64-migrupgrade 22 guest-migrate/src_host/dst_host fail 
>>>>> REGR. vs. 
>>> 128084
>>>>
>>>> At the first glance
>>>>
>>>> libxl: error: libxl_sched.c:232:sched_credit_domain_set: Domain 1:Getting 
>>> domain sched credit: Invalid argument
>>>> libxl: error: libxl_create.c:1275:domcreate_rebuild_done: Domain 1:cannot 
>>> (re-)build domain: -3
>>>>
>>>> might indicate a problem resulting from the switch to credit2 as the 
>>>> default
>>>> scheduler. But "first glance" here really means what it says - I didn't 
>>>> look
>>>> (yet) at what exactly libxl tries to do there, in the hope that others may
>>>> know without much digging.
>>>
>>> I think this is due to toolstack trying to set the same scheduler
>>> parameters for the newly created guest.
>>>
>>> But in this test, the destination host is using a different scheduler
>>> from the source host. Asking for credit scheduler on a credit2 host is
>>> wrong.
>>>
>>> The relevant snippet in guest cfg (JSON) is:
>>>
>>>                 "sched_params": {
>>>                     "sched": "credit",
>>>                     "weight": 256,
>>>                     "cap": 0
>>>                 },
>>>
>>> I can't think of a method to fix it off the top of my head though.
>>
>> So is this something that was specified in the original config? Or
>> is it just the current value which gets read and an attempt made
>> to re-install. If there was no explicit setting in the guest config,
>> shouldn't such a "default" setting be retained by not transferring
>> any scheduler specifics during migration?
>>
> 
> No setting in guest cfg. Those values are extracted from the hypervisor.
> I think we may be able to not send default values to the remote end.

Wait, the migration code reads the scheduler parameters -- even if these
have not been explicitly set by the admin -- and sends them along with
the migration stream?  And if the remote scheduler is different, the
migration fails?

That's not so good. :-)

 -George


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