Re: [Xen-devel] domains being migrated state message improvements

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2014-05-02 at 14:40 +0100, Andrew Cooper wrote:
> On 02/05/14 14:29, Ian Campbell wrote:
> >
> >> I would agree that it is a little confusing.  '------' means runnable
> >> but not running, in this case due to vcpu over subscription.
> > Is that not "blocked"?
> 
> Blocked is any vcpu/domain pause count.  For healthy domains, this is
> usually a yielded timeslice, which is why idle domains are almost always
> '-b----'.
> 
> >
> > BTW, the "migration" referred to here is VCPU migration to another PCPU
> > rather than domain migration. (It came up because that's another one of
> > the VCPU pause flags alongside blocked et al)
> 
> I do not think vcpu motion around the system is actually relevant to the
> problem described.

It was due to this code in getdomaininfo:
    /* 
     * - domain is marked as blocked only if all its vcpus are blocked
     * - domain is marked as running if any of its vcpus is running
     */
    for_each_vcpu ( d, v )
    {
        vcpu_runstate_get(v, &runstate);
        cpu_time += runstate.time[RUNSTATE_running];
        info->max_vcpu_id = v->vcpu_id;
        if ( !test_bit(_VPF_down, &v->pause_flags) )
        {
            if ( !(v->pause_flags & VPF_blocked) )
                flags &= ~XEN_DOMINF_blocked;
            if ( v->is_running )
                flags |= XEN_DOMINF_running;
            info->nr_online_vcpus++;
        }
    }

If a domain was not running or blocked then it could end up with neither
set, I thought this might be when some other VPF was applied, like
VPF_migrating (or VPF_mem_paging etc).

Or are you saying that those always come along with a VPF_blocked?

Ian.


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