Re: [2.6.20][PATCH] fix mempolicy error check on a system with memory-less-node

Christoph Lameter
2007-02-08T19:09:53Z

On Wed, 7 Feb 2007, Andrew Morton wrote:

> > > A node which has CPUs and no memory is obviously physically possible and
> > > isn't a completely insane thing for a user to do. I'd have thought that
> > > the kernel should be able to cleanly and clearly handle it,
> >
> > It doesn't.
>
> Fix it?

Why? It is a bad idea.

> > > and to
> > > accurately present the machine's topology to the user without us having to
> > > go adding falsehoods like this?
> >
> > a node is a piece of memory. Without memory it doesn't make sense.
>
> Who said? I can pick up a piece of circuitry which has four CPUs and no
> RAM, wave it about then stick it in a computer. The kernel is just wrong,
> surely?

Surely your computer has some memory so attach it to that memory (which
in a NUMA system would be one or the other node).

Cpu only "nodes" would mean that all memory would be off node. Meaning
whatever interconnect one has would be heavily used. Operating system and
application performance will suffer.