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

Peter Zijlstra
2012-03-16T21:13:38Z

On Fri, 2012-03-16 at 13:34 -0500, Christoph Lameter wrote:
> On Fri, 16 Mar 2012, Peter Zijlstra wrote:
>
> > Add another layer of fallback policy to make the home node concept
> > useful from a memory allocation PoV.
> >
> > This changes the mpol order to:
> >
> > - vma->vm_ops->get_policy [if applicable]
> > - vma->vm_policy [if applicable]
> > - task->mempolicy
> > - tsk_home_node() preferred [NEW]
> > - default_policy
> >
> > 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.