On Fri 08-12-17 12:42:55, changbin.du@xxxxxxxxx wrote:
> From: Changbin Du <changbin.du@xxxxxxxxx>
>
> This patch introduced 4 new interfaces to allocate a prepared transparent
> huge page. These interfaces merge distributed two-step allocation as simple
> single step. And they can avoid issue like forget to call prep_transhuge_page()
> or call it on wrong page. A real fix:
> 40a899e ("mm: migrate: fix an incorrect call of prep_transhuge_page()")
>
> Anyway, I just want to prove that expose direct allocation interfaces is
> better than a interface only do the second part of it.
>
> These are similar to alloc_hugepage_xxx which are for hugetlbfs pages. New
> interfaces are:
> - alloc_transhuge_page_vma
> - alloc_transhuge_page_nodemask
> - alloc_transhuge_page_node
> - alloc_transhuge_page
>
> These interfaces implicitly add __GFP_COMP gfp mask which is the minimum
> flags used for huge page allocation. More flags leave to the callers.
>
> This patch does below changes:
> - define alloc_transhuge_page_xxx interfaces
> - apply them to all existing code
> - declare prep_transhuge_page as static since no others use it
> - remove alloc_hugepage_vma definition since it no longer has users
I am not really convinced this is a huge win, to be honest. Just look at
the diffstat. Very few callsites get marginally simpler while we add a
lot of stubs and the code churn.
> Signed-off-by: Changbin Du <changbin.du@xxxxxxxxx>
>
> ---
> v4:
> - Revise the nop function definition. (Andrew)
>
> v3:
> - Rebase to latest mainline.
>
> v2:
> Anshuman Khandu:
> - Remove redundant 'VM_BUG_ON(!(gfp_mask & __GFP_COMP))'.
> Andrew Morton:
> - Fix build error if thp is disabled.
> ---
> include/linux/gfp.h | 4 ----
> include/linux/huge_mm.h | 35 +++++++++++++++++++++++++++++++++--
> include/linux/migrate.h | 14 +++++---------
> mm/huge_memory.c | 48 +++++++++++++++++++++++++++++++++++++++++-------
> mm/khugepaged.c | 11 ++---------
> mm/mempolicy.c | 14 +++-----------
> mm/migrate.c | 14 ++++----------
> mm/shmem.c | 6 ++----
> 8 files changed, 90 insertions(+), 56 deletions(-)
--
Michal Hocko
SUSE Labs
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