Re: [PATCH 1/2] mm: fix remote numa hits statistics

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On Thu 29-12-16 11:46:01, Mel Gorman wrote:
> On Wed, Dec 21, 2016 at 09:06:52AM +0100, Michal Hocko wrote:
> > From: Michal Hocko <mhocko@xxxxxxxx>
> > 
> > Jia He has noticed that b9f00e147f27 ("mm, page_alloc: reduce branches
> > in zone_statistics") has an unintentional side effect that remote node
> > allocation requests are accounted as NUMA_MISS rathat than NUMA_HIT and
> > NUMA_OTHER if such a request doesn't use __GFP_OTHER_NODE. There are
> > many of these potentially because the flag is used very rarely while
> > we have many users of __alloc_pages_node.
> > 
> > Fix this by simply ignoring __GFP_OTHER_NODE (it can be removed in a
> > follow up patch) and treat all allocations that were satisfied from the
> > preferred zone's node as NUMA_HITS because this is the same node we
> > requested the allocation from in most cases. If this is not the local
> > node then we just account it as NUMA_OTHER rather than NUMA_LOCAL.
> > 
> > One downsize would be that an allocation request for a node which is
> > outside of the mempolicy nodemask would be reported as a hit which is a
> > bit weird but that was the case before b9f00e147f27 already.
> > 
> > Reported-by: Jia He <hejianet@xxxxxxxxx>
> > Fixes: b9f00e147f27 ("mm, page_alloc: reduce branches in zone_statistics")
> > Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
> 
> For both patches;
> 
> Acked-by: Mel Gorman <mgorman@xxxxxxx>

Thanks! I will give it a week for others to get back to it after holiday
and then resubmit.
-- 
Michal Hocko
SUSE Labs

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