Re: [RFC][PATCH 10/26] mm, mpol: Make mempolicy home-node aware

Peter Zijlstra
2012-03-19T14:06:50Z

On Mon, 2012-03-19 at 08:53 -0500, Christoph Lameter wrote:
> On Fri, 16 Mar 2012, Peter Zijlstra wrote:
>
> > > > Note that the tsk_home_node() policy has Migrate-on-Fault enabled to
> > > > facilitate efficient on-demand memory migration.
> > >
> > > The numa hierachy is already complex. Could we avoid adding another layer
> > > by adding a MPOL_HOME_NODE and make that the default?
> >
> > Not sure that's really a win, the behaviour would be the same we just
> > have to implement another policy, which is likely more code.
>
> A HOME_NODE policy would also help to ensure that existing applications
> continue to work as expected. Given that people in the HPC industry and
> elsewhere have been fine tuning around the scheduler for years this is a
> desirable goal and ensures backward compatibility.

I really have no idea what you're saying. Existing applications that use
mbind/set_mempolicy already continue to function exactly like before,
see how the new layer is below all that.