Re: [Xen-devel] [PATCH] cpupools: retry cpupool-destroy if domain in cpupool is dying

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

On Wed, May 7, 2014 at 2:23 PM, Juergen Gross
<juergen.gross@xxxxxxxxxxxxxx> wrote:
> On 07.05.2014 15:10, George Dunlap wrote:
>>
>> On Wed, May 7, 2014 at 8:52 AM, Juergen Gross
>> <juergen.gross@xxxxxxxxxxxxxx> wrote:
>>>
>>> When a cpupool is destroyed just after the last domain has been stopped
>>> the
>>> domain might already be removed from the cpupool without having
>>> decremented
>>> the domain count of the cpupool. This will result in rejection of the
>>> cpupool-destroy operation.
>>
>>
>> I'm a bit confused.  What's the sched_move_domain() for, then?  If
>> we're going to handle "dying domains" by doing a retry, could we just
>> get rid of it?
>
>
> The sched_move_domain() is still needed for cases where a domain stays
> dying for a longer time, e.g. when a dom0 process is still referencing
> some of it's memory pages. This may be a rare situation, but being unable
> to use a physical cpu for another cpupool just because of this case is
> worse than this little piece of code, IMO.

And I take it there are times when the move fails for whatever reason?

Could you add a comment explaining this above the for() loop then, for
posterity?

 -George

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