Re: [PATCH V2] mm/thp: Allocate transparent hugepages on local node

From: Aneesh Kumar K.V
Date: Wed Dec 03 2014 - 10:43:39 EST

Vlastimil Babka <vbabka@xxxxxxx> writes:

> On 12/01/2014 03:06 PM, Aneesh Kumar K.V wrote:
>> "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx> writes:
>>> On Mon, Dec 01, 2014 at 11:16:43AM +0530, Aneesh Kumar K.V wrote:
>>>> This make sure that we try to allocate hugepages from local node if
>>>> allowed by mempolicy. If we can't, we fallback to small page allocation
>>>> based on mempolicy. This is based on the observation that allocating pages
>>>> on local node is more beneficial that allocating hugepages on remote node.

>>>> index e58725aff7e9..fa96af5b31f7 100644
>>>> --- a/mm/mempolicy.c
>>>> +++ b/mm/mempolicy.c
>>>> @@ -2041,6 +2041,46 @@ retry_cpuset:
>>>> return page;
>>>> }
>>>> +struct page *alloc_hugepage_vma(gfp_t gfp, struct vm_area_struct *vma,
>>>> + unsigned long addr, int order)
> It's somewhat confusing that the name talks about hugepages, yet you
> have to supply the order and gfp. Only the policy handling is tailored
> for hugepages. But maybe it's better than calling the function
> "alloc_pages_vma_local_only_unless_interpolate" :/

I did try to do an API that does

struct page *alloc_hugepage_vma(struct vm_area_struct *vma, unsigned long addr)

But that will result in further #ifdef in mm/mempolicy, because we will
then introduce transparent_hugepage_defrag(vma) and HPAGE_PMD_ORDER
there. I was not sure whether we really wanted that.


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