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Date: Thu, 29 Dec 2016 11:46:01 +0000
From: Mel Gorman <mgorman@suse.de>
Subject: Re: [PATCH 1/2] mm: fix remote numa hits statistics
Message-ID: <20161229114601.wuadp2l6xwzdxv6s@suse.de>
References: <20161221075711.GF16502@dhcp22.suse.cz>
 <20161221080653.29437-1-mhocko@kernel.org>
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To: Michal Hocko <mhocko@kernel.org>
Cc: linux-mm@kvack.org, Vlastimil Babka <vbabka@suse.cz>, Andrew Morton <akpm@linux-foundation.org>, Joonsoo Kim <js1304@gmail.com>, Jia He <hejianet@gmail.com>, Taku Izumi <izumi.taku@jp.fujitsu.com>, Johannes Weiner <hannes@cmpxchg.org>, Michal Hocko <mhocko@suse.com>

On Wed, Dec 21, 2016 at 09:06:52AM +0100, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> 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@gmail.com>
> Fixes: b9f00e147f27 ("mm, page_alloc: reduce branches in zone_statistics")
> Signed-off-by: Michal Hocko <mhocko@suse.com>

For both patches;

Acked-by: Mel Gorman <mgorman@suse.de>

-- 
Mel Gorman
SUSE Labs

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