From: Minchan Kim <minchan@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: 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>,
Joel Fernandes <joel@joelfernandes.org>,
Alexander Duyck <alexander.h.duyck@linux.intel.com>,
Minchan Kim <minchan@kernel.org>
Subject: [PATCH v4 6/8] mm/madvise: allow KSM hints for remote API
Date: Wed, 12 Feb 2020 15:39:44 -0800 [thread overview]
Message-ID: <20200212233946.246210-7-minchan@kernel.org> (raw)
In-Reply-To: <20200212233946.246210-1-minchan@kernel.org>
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>
---
mm/madvise.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/mm/madvise.c b/mm/madvise.c
index 71f0ba199ae8..b1237466657e 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -1002,6 +1002,10 @@ process_madvise_behavior_valid(int behavior)
switch (behavior) {
case MADV_COLD:
case MADV_PAGEOUT:
+#ifdef CONFIG_KSM
+ case MADV_MERGEABLE:
+ case MADV_UNMERGEABLE:
+#endif
return true;
default:
return false;
--
2.25.0.225.g125e21ebc7-goog
next prev parent reply other threads:[~2020-02-12 23:40 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-12 23:39 [PATCH v4 0/8] introduce memory hinting API for external process Minchan Kim
2020-02-12 23:39 ` [PATCH v4 1/8] mm: pass task to do_madvise Minchan Kim
2020-02-13 0:21 ` Alexander Duyck
2020-02-13 17:02 ` Minchan Kim
2020-02-13 17:35 ` Jann Horn
2020-02-12 23:39 ` [PATCH v4 2/8] mm: introduce external memory hinting API Minchan Kim
2020-02-13 14:08 ` Jann Horn
2020-02-13 16:10 ` Minchan Kim
2020-02-12 23:39 ` [PATCH v4 3/8] mm: validate mm in do_madvise Minchan Kim
2020-02-12 23:39 ` [PATCH v4 4/8] mm: check fatal signal pending of target process Minchan Kim
2020-02-12 23:39 ` [PATCH v4 5/8] mm/madvise: employ mmget_still_valid for write lock Minchan Kim
2020-02-12 23:39 ` Minchan Kim [this message]
2020-02-12 23:39 ` [PATCH v4 7/8] pid: export pidfd_get_pid Minchan Kim
2020-02-13 0:25 ` Alexander Duyck
2020-02-13 17:08 ` Minchan Kim
2020-02-12 23:39 ` [PATCH v4 8/8] mm: support both pid and pidfd for process_madvise Minchan Kim
2020-02-13 0:28 ` Alexander Duyck
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