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

[Christoph Lameter]

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.


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/