Re: [PATCH 20/31] sched, numa, mm/mpol: Make mempolicy home-nodeaware

[Mel Gorman]

On Thu, Oct 25, 2012 at 02:16:37PM +0200, 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.
> 

Makes sense and it looks like a VMA policy, if set, will still override
the home_node policy as you'd expect. At some point this may need to cope
with node hot-remove. Also, at some point this must be dealing with the
case where mbind() is called but the home_node is not in the nodemask.
Does that happen somewhere else in the series? (maybe I'll see it later)

-- 
Mel Gorman
SUSE Labs
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