From: Oleksandr Natalenko <oleksandr@redhat.com>
To: Michal Hocko <mhocko@kernel.org>
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
Date: Wed, 15 May 2019 09:37:23 +0200 [thread overview]
Message-ID: <20190515073723.wbr522cpyjfelfav@butterfly.localdomain> (raw)
In-Reply-To: <20190515065311.GB16651@dhcp22.suse.cz>
Hi.
On Wed, May 15, 2019 at 08:53:11AM +0200, Michal Hocko wrote:
> 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.
For my current setup with 2 Firefox instances I get 100 to 200 MiB saved
for the second instance depending on the amount of tabs.
1 FF instance with 15 tabs:
$ echo "$(cat /sys/kernel/mm/ksm/pages_sharing) * 4 / 1024" | bc
410
2 FF instances, second one has 12 tabs (all the tabs are different):
$ echo "$(cat /sys/kernel/mm/ksm/pages_sharing) * 4 / 1024" | bc
592
At the very moment I do not have specific numbers for containerised
workload, but those should be similar in case the containers share
similar/same runtime (like multiple Node.js containers etc).
Answering your question regarding using existing interfaces, since
there's only one, madvise(2), this requires modifying all the
applications one wants to de-duplicate. In case of containers with
arbitrary content or in case of binary-only apps this is pretty hard if
not impossible to do properly.
> 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.
Sure, please do.
Thanks for your time and inputs.
--
Best regards,
Oleksandr Natalenko (post-factum)
Senior Software Maintenance Engineer
next prev parent reply other threads:[~2019-05-15 7:37 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-14 13:16 [PATCH RFC v2 0/4] mm/ksm: add option to automerge VMAs 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 [this message]
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
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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