linux-kernel - Re: [PATCH v3] resource: Merge resources on a node when hot-adding memory

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Message-ID: <20180810130052.GC1644@dhcp22.suse.cz>
Date:   Fri, 10 Aug 2018 15:00:52 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Rashmica Gupta <rashmica.g@...il.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, toshi.kani@....com,
        tglx@...utronix.de, bp@...e.de, brijesh.singh@....com,
        thomas.lendacky@....com, jglisse@...hat.com,
        gregkh@...uxfoundation.org, baiyaowei@...s.chinamobile.com,
        dan.j.williams@...el.com, iamjoonsoo.kim@....com,
        Vlastimil Babka <vbabka@...e.cz>, malat@...ian.org,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        osalvador@...hadventures.net, yasu.isimatu@...il.com,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>
Subject: Re: [PATCH v3] resource: Merge resources on a node when hot-adding
 memory

On Fri 10-08-18 16:55:40, Rashmica Gupta wrote:
[...]
> Most memory hotplug/hotremove seems to be block or section based, and
> always adds and removes memory at the same place.

Yes and that is hard wired to the memory hotplug code. It is not easy to
make it work outside of section units restriction. So whatever your
memtrace is doing and if it relies on subsection hotplug it cannot
possibly work with the current code.

I didn't get to review your patch but if it is only needed for an
unmerged code I would rather incline to not merge it unless it is a
clear win to the resource subsystem. A report from Oscar shows that this
is not the case though.

-- 
Michal Hocko
SUSE Labs