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Date:   Wed, 15 May 2019 08:53:11 +0200
From:   Michal Hocko <mhocko@kernel.org>
To:     Oleksandr Natalenko <oleksandr@redhat.com>
Cc:     linux-kernel@vger.kernel.org, Kirill Tkhai <ktkhai@virtuozzo.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Matthew Wilcox <willy@infradead.org>,
        Pavel Tatashin <pasha.tatashin@soleen.com>,
        Timofey Titovets <nefelim4ag@gmail.com>,
        Aaron Tomlin <atomlin@redhat.com>,
        Grzegorz Halat <ghalat@redhat.com>, linux-mm@kvack.org,
        linux-api@vger.kernel.org, Hugh Dickins <hughd@google.com>
Subject: Re: [PATCH RFC v2 0/4] mm/ksm: add option to automerge VMAs
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On Wed 15-05-19 08:25:23, Oleksandr Natalenko wrote:
[...]
> > > Please make sure to describe a usecase that warrants adding a new
> > > interface we have to maintain for ever.
> 
> I think of two major consumers of this interface:
> 
> 1) hosts, that run containers, especially similar ones and especially in
> a trusted environment;
> 
> 2) heavy applications, that can be run in multiple instances, not
> limited to opensource ones like Firefox, but also those that cannot be
> modified.

This is way too generic. Please provide something more specific. Ideally
with numbers. Why those usecases cannot use an existing interfaces.
Remember you are trying to add a new user interface which we will have
to maintain for ever.

I will try to comment on the interface itself later. But I have to say
that I am not impressed. Abusing sysfs for per process features is quite
gross to be honest.

-- 
Michal Hocko
SUSE Labs