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Subject: Re: [RFC v1 00/19] Modify zonelist to nodelist v1
To:     Pengfei Li <fly@kernel.page>, akpm@linux-foundation.org
Cc:     mgorman@techsingularity.net, mhocko@kernel.org, vbabka@suse.cz,
        cl@linux.com, iamjoonsoo.kim@lge.com, guro@fb.com,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org
References: <20191121151811.49742-1-fly@kernel.page>
From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat GmbH
Message-ID: <1bb37491-72a7-feaa-722d-a5825813a409@redhat.com>
Date:   Fri, 22 Nov 2019 11:03:30 +0100
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On 21.11.19 16:17, Pengfei Li wrote:
> Motivation
> ----------
> Currently if we want to iterate through all the nodes we have to
> traverse all the zones from the zonelist.
>=20
> So in order to reduce the number of loops required to traverse node,
> this series of patches modified the zonelist to nodelist.
>=20
> Two new macros have been introduced:
> 1) for_each_node_nlist
> 2) for_each_node_nlist_nodemask
>=20
>=20
> Benefit
> -------
> 1. For a NUMA system with N nodes, each node has M zones, the number
>     of loops is reduced from N*M times to N times when traversing node.
>=20
> 2. The size of pg_data_t is much reduced.
>=20
>=20
> Test Result
> -----------
> Currently I have only performed a simple page allocation benchmark
> test on my laptop, and the results show that the performance of a
> system with only one node is almost unaffected.
>=20

So you are seeing no performance changes. I am wondering why do we need=20
this, then - because your motivation sounds like a performance=20
improvement? (not completely against this, just trying to understand the=20
value of this :) )


--=20

Thanks,

David / dhildenb