Re: [Xen-devel] [PATCH 3/4] libxc: rework vnuma bits in setup_guest

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, May 19, 2015 at 06:14:27PM +0100, Wei Liu wrote:
[...]
> > >>
> > >>Does having high memory mean that we need to have 2 vnodes? We should be
> > >Yes, see the comment above.
> > >
> > >>able to cope with multiple vmemranges per node, right?
> > >
> > >Yes. That's already done in libxl's function to build hvm vmemranges.
> > >
> > >This is only a simple dummy layout so nothing fancy happens here.
> > 
> > 
> > Right. But having multiple vnodes for a dummy topology looks to me a little
> > counter-intuitive: people often assume that when number of nodes is 1 we
> > don't have any NUMA-ness. Here we may need to look at vnode_to_pnode
> > (possibly at both of the elements) to realize that this is a dummy layout.
> > 
> > And given that this layout can be expressed with nr_vnodes=1 &&
> > nr_vmemranges=2 I am not sure what we gain by having two vnodes.
> > 
> 
> Ah, so that's a bug: args->nr_vnodes++ should be deleted.
> 
> We still only have one vnode (nid = 0). That vnode contains two
> vmemranges.
> 

And because no code in setup_guest uses that value so the bug doesn't
affect the final guest layout. It will be fixed in version 2
nonetheless.

Wei.

> Wei.
> 
> > -boris
> > 
> > >
> > >Wei.
> > >
> > >>-boris
> > >>
> > >>
> > >>>+        }
> > >>>+
> > >>>+        args->vmemranges = dummy_vmemrange;
> > >>>+        args->vnode_to_pnode = dummy_vnode_to_pnode;
> > >>>      }
> > >>>

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