From: SeongJae Park <sj38.park@gmail.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
linux-api@vger.kernel.org, oleksandr@redhat.com,
Suren Baghdasaryan <surenb@google.com>,
Tim Murray <timmurray@google.com>,
Daniel Colascione <dancol@google.com>,
Sandeep Patil <sspatil@google.com>,
Sonny Rao <sonnyrao@google.com>,
Brian Geffon <bgeffon@google.com>, Michal Hocko <mhocko@suse.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Shakeel Butt <shakeelb@google.com>,
John Dias <joaodias@google.com>
Subject: Re: [PATCH 4/4] mm/madvise: allow KSM hints for remote API
Date: Sat, 11 Jan 2020 08:42:59 +0100 [thread overview]
Message-ID: <20200111074259.25577-1-sj38.park@gmail.com> (raw)
In-Reply-To: <20200110213433.94739-5-minchan@kernel.org> (raw)
On Fri, 10 Jan 2020 13:34:33 -0800 Minchan Kim <minchan@kernel.org> wrote:
> From: Oleksandr Natalenko <oleksandr@redhat.com>
>
> It all began with the fact that KSM works only on memory that is marked
> by madvise(). And the only way to get around that is to either:
>
> * use LD_PRELOAD; or
> * patch the kernel with something like UKSM or PKSM.
>
> (i skip ptrace can of worms here intentionally)
>
> To overcome this restriction, lets employ a new remote madvise API. This
> can be used by some small userspace helper daemon that will do auto-KSM
> job for us.
>
> I think of two major consumers of remote KSM hints:
>
> * hosts, that run containers, especially similar ones and especially in
> a trusted environment, sharing the same runtime like Node.js;
>
> * heavy applications, that can be run in multiple instances, not
> limited to opensource ones like Firefox, but also those that cannot be
> modified since they are binary-only and, maybe, statically linked.
>
> Speaking of statistics, more numbers can be found in the very first
> submission, that is related to this one [1]. For my current setup with
> two 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 comparable in case the containers share
> similar/same runtime.
>
> [1] https://lore.kernel.org/patchwork/patch/1012142/
>
> Signed-off-by: Oleksandr Natalenko <oleksandr@redhat.com>
> Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: SeongJae Park <sjpark@amazon.de>
> ---
> mm/madvise.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/mm/madvise.c b/mm/madvise.c
> index eb42b2b7f49b..3aa9aec6bfd9 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -1000,6 +1000,8 @@ process_madvise_behavior_valid(int behavior)
> switch (behavior) {
> case MADV_COLD:
> case MADV_PAGEOUT:
> + case MADV_MERGEABLE:
> + case MADV_UNMERGEABLE:
> return true;
> default:
> return false;
> --
> 2.25.0.rc1.283.g88dfdc4193-goog
prev parent reply other threads:[~2020-01-11 7:43 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-10 21:34 [PATCH 0/4] introduce memory hinting API for external process Minchan Kim
2020-01-10 21:34 ` [PATCH 1/4] mm: factor out madvise's core functionality Minchan Kim
2020-01-11 7:37 ` SeongJae Park
2020-01-13 18:11 ` Minchan Kim
2020-01-13 18:22 ` SeongJae Park
2020-01-10 21:34 ` [PATCH 2/4] mm: introduce external memory hinting API Minchan Kim
2020-01-11 7:34 ` SeongJae Park
2020-01-13 18:02 ` Minchan Kim
2020-01-13 8:47 ` Kirill Tkhai
2020-01-13 10:42 ` Christian Brauner
2020-01-13 18:44 ` Minchan Kim
2020-01-13 19:10 ` Christian Brauner
2020-01-13 19:27 ` Daniel Colascione
2020-01-13 20:42 ` Christian Brauner
2020-01-13 21:04 ` Daniel Colascione
2020-01-14 19:20 ` Christian Brauner
2020-01-14 18:59 ` Minchan Kim
2020-01-14 19:22 ` Christian Brauner
2020-01-13 18:39 ` Minchan Kim
2020-01-13 19:18 ` Daniel Colascione
2020-01-14 8:39 ` Kirill Tkhai
2020-01-14 19:12 ` Minchan Kim
2020-01-15 9:38 ` Kirill Tkhai
2020-01-10 21:34 ` [PATCH 3/4] mm/madvise: employ mmget_still_valid for write lock Minchan Kim
2020-01-10 21:34 ` [PATCH 4/4] mm/madvise: allow KSM hints for remote API Minchan Kim
2020-01-11 7:42 ` SeongJae Park [this message]
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