Re: [Qemu-devel] [PATCH 11/18] migration: introduce capability localhost

[Lei Li]

On 08/23/2013 03:40 PM, Paolo Bonzini wrote:
> Il 22/08/2013 22:50, Michael R. Hines ha scritto:
> > On 08/21/2013 11:18 AM, Paolo Bonzini wrote:
> > > Il 21/08/2013 09:18, Lei Li ha scritto:
> > > >        } else if (strstart(uri, "unix:", &p)) {
> > > > +        if (s->enabled_capabilities[MIGRATION_CAPABILITY_LOCALHOST]) {
> > > > +            local_start_outgoing_migration(s, p, &local_err);
> > > > +        }
> > > >            unix_start_outgoing_migration(s, p, &local_err);
> > > >        } else if (strstart(uri, "fd:", &p)) {
> > > >            fd_start_outgoing_migration(s, p, &local_err);
> > > > @@ -521,6 +524,15 @@ int migrate_use_xbzrle(void)
> > > >        return s->enabled_capabilities[MIGRATION_CAPABILITY_XBZRLE];
> > > >    }
> > > >    +bool migrate_is_localhost(void)
> > > > +{
> > > > +    MigrationState *s;
> > > > +
> > > > +    s = migrate_get_current();
> > > > +
> > > > +    return s->enabled_capabilities[MIGRATION_CAPABILITY_LOCALHOST];
> > > > +}
> > > I think this is a bad name, too.  There is nothing more "local" in this
> > > migration than in "unix:" migration.
> > >
> > > Let's call the capability according to what it does, for example
> > > unix-page-flipping.
> > Why is there a capability at all? Isn't that what the "local" URI is for?
> Because in these patches, the local URI is only present in the
> destination (which is wrong: the destination should autodetect local
> mode using the load-page hook).  As you can see above, a "unix" URI will
> examine the capability and pick the appropriate migration method.

Hi Paolo,

I agree with that 'localhost' is a bad capability name. Since we just use unix
socket temporarily and will be ending up with vmsplice via pipe, how about
just page_flipping?

> However, this is also the wrong place to look at the capability.  It is
> the save-page hook that should examine the capability.  It will then do
> nothing if it is disabled, and do page-flipping if the capability is on.
>
> Paolo


--
Lei