Re: [PATCH] mm, thp: relax __GFP_THISNODE for MADV_HUGEPAGE mappings

[Vlastimil Babka]

On 09/10/2018 10:08 PM, David Rientjes wrote:
> When Andrea brought this up, I suggested that the full solution would be a 
> MPOL_F_HUGEPAGE flag that could define thp allocation policy -- the added 

Can you elaborate on the semantics of this? You mean that a given vma
could now have two mempolicies, where one would be for hugepages only?
That's likely much more easy to suggest than to implement, with all uapi
consequences...

> benefit is that we could replace the thp "defrag" mode default by setting 
> this as part of default_policy.  Right now, MADV_HUGEPAGE users are 
> concerned about (1) getting thp when system-wide it is not default and (2) 
> additional fault latency when direct compaction is not default.  They are 
> not anticipating the degradation of remote access latency, so overloading 
> the meaning of the mode is probably not a good idea.
>