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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>,
	Suren Baghdasaryan <surenb@google.com>,
	Minchan Kim <minchan@kernel.org>
Subject: Re: [PATCH RFC v2 0/4] mm/ksm: add option to automerge VMAs
Date: Wed, 15 May 2019 16:51:51 +0200
Message-ID: <20190515145151.GG16651@dhcp22.suse.cz> (raw)
In-Reply-To: <20190515065311.GB16651@dhcp22.suse.cz>

[Cc Suren and Minchan - the email thread starts here 20190514131654.25463-1-oleksandr@redhat.com]

On Wed 15-05-19 08:53:11, Michal Hocko wrote:
[...]
> 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.

I have already commented on this in other email. I consider sysfs an
unsuitable interface for per-process API. Not to mention this particular
one is very KSM specific while the question about setting different
hints on memory of a remote process is a more generic question. As
already mentioned there are usecases where people would like to say
that a certain memory is cold from outside of the process context (e.g.
monitor application). So essentially a form of a user space memory
management. And this usecase sounds a bit similar to me and having a
common api sounds more sensible to me.

One thing we were discussing at LSFMM this year was a way to either
provide madvise_remote(pid, addr, length, advice) or a fadvise
alternative over /proc/<pid>/map_vmas/<range> file descriptors
(essentially resembling the existing map_files api) to achieve such a
functionality. This is still a very rough idea but the api would sound
much more generic to me and it would allow much wider range of usecases.

But maybe I am completely wrong and this is just opens a can of worms
that we do not want.
-- 
Michal Hocko
SUSE Labs


  parent reply index

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-14 13:16 Oleksandr Natalenko
2019-05-14 13:16 ` [PATCH RFC v2 1/4] mm/ksm: introduce ksm_enter() helper Oleksandr Natalenko
2019-05-14 13:16 ` [PATCH RFC v2 2/4] mm/ksm: introduce ksm_leave() helper Oleksandr Natalenko
2019-05-14 13:16 ` [PATCH RFC v2 3/4] mm/ksm: introduce force_madvise knob Oleksandr Natalenko
2019-05-14 13:22   ` Aaron Tomlin
2019-05-15  0:48     ` Timofey Titovets
2019-05-14 13:16 ` [PATCH RFC v2 4/4] mm/ksm: add force merging/unmerging documentation Oleksandr Natalenko
2019-05-15  0:53   ` Timofey Titovets
2019-05-15  6:26     ` Oleksandr Natalenko
2019-05-14 14:41 ` [PATCH RFC v2 0/4] mm/ksm: add option to automerge VMAs Michal Hocko
2019-05-14 14:51   ` Michal Hocko
2019-05-15  6:25     ` Oleksandr Natalenko
2019-05-15  6:53       ` Michal Hocko
2019-05-15  7:37         ` Oleksandr Natalenko
2019-05-15  8:33           ` Michal Hocko
2019-05-15  8:51             ` Oleksandr Natalenko
2019-05-15 14:24               ` Michal Hocko
2019-05-15 14:51         ` Michal Hocko [this message]
2019-05-15 15:15           ` Greg KH
2019-05-16  7:47             ` Michal Hocko
2019-05-16  7:53               ` Greg KH

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