Re: [RFC PATCH 2/4] hugetlb: add support for preferred node to alloc_huge_page_nodemask

[Michal Hocko]

On Wed 14-06-17 17:12:31, Mike Kravetz wrote:
> On 06/14/2017 03:12 PM, Mike Kravetz wrote:
> > On 06/13/2017 02:00 AM, Michal Hocko wrote:
> >> From: Michal Hocko <mhocko@xxxxxxxx>
> >>
> >> alloc_huge_page_nodemask tries to allocate from any numa node in the
> >> allowed node mask starting from lower numa nodes. This might lead to
> >> filling up those low NUMA nodes while others are not used. We can reduce
> >> this risk by introducing a concept of the preferred node similar to what
> >> we have in the regular page allocator. We will start allocating from the
> >> preferred nid and then iterate over all allowed nodes in the zonelist
> >> order until we try them all.
> >>
> >> This is mimicking the page allocator logic except it operates on
> >> per-node mempools. dequeue_huge_page_vma already does this so distill
> >> the zonelist logic into a more generic dequeue_huge_page_nodemask
> >> and use it in alloc_huge_page_nodemask.
> >>
> >> Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
> >> ---
> > 
> > 
> > I built attempts/hugetlb-zonelists, threw it on a test machine, ran the
> > libhugetlbfs test suite and saw failures.  The failures started with this
> > patch: commit 7e8b09f14495 in your tree.  I have not yet started to look
> > into the failures.  It is even possible that the tests are making bad
> > assumptions, but there certainly appears to be changes in behavior visible
> > to the application(s).
> 
> nm.  The failures were the result of dequeue_huge_page_nodemask() always
> returning NULL.  Vlastimil already noticed this issue and provided a
> solution.

I have pushed my current version to the same branch.
-- 
Michal Hocko
SUSE Labs