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Message-ID: <43d64aee-4bd9-bba0-9434-55cec26bd9dc@redhat.com>
Date: Tue, 15 Aug 2023 09:19:22 +0200
From: David Hildenbrand <david@...hat.com>
To: Stefan Roesch <shr@...kernel.io>, kernel-team@...com
Cc: akpm@...ux-foundation.org, linux-fsdevel@...r.kernel.org,
hannes@...xchg.org, riel@...riel.com, linux-kernel@...r.kernel.org,
linux-mm@...ck.org
Subject: Re: [PATCH v2] proc/ksm: add ksm stats to /proc/pid/smaps
Sorry for the late reply, Gmail once again decided to classify your
mails as spam (for whatever reason).
On 11.08.23 18:28, Stefan Roesch wrote:
> With madvise and prctl KSM can be enabled for different VMA's. Once it
> is enabled we can query how effective KSM is overall. However we cannot
> easily query if an individual VMA benefits from KSM.
>
> This commit adds a KSM section to the /prod/<pid>/smaps file. It reports
> how many of the pages are KSM pages.
>
> Here is a typical output:
>
> 7f420a000000-7f421a000000 rw-p 00000000 00:00 0
> Size: 262144 kB
> KernelPageSize: 4 kB
> MMUPageSize: 4 kB
> Rss: 51212 kB
> Pss: 8276 kB
> Shared_Clean: 172 kB
> Shared_Dirty: 42996 kB
> Private_Clean: 196 kB
> Private_Dirty: 7848 kB
> Referenced: 15388 kB
> Anonymous: 51212 kB
> KSM: 41376 kB
> LazyFree: 0 kB
> AnonHugePages: 0 kB
> ShmemPmdMapped: 0 kB
> FilePmdMapped: 0 kB
> Shared_Hugetlb: 0 kB
> Private_Hugetlb: 0 kB
> Swap: 202016 kB
> SwapPss: 3882 kB
> Locked: 0 kB
> THPeligible: 0
> ProtectionKey: 0
> ksm_state: 0
> ksm_skip_base: 0
> ksm_skip_count: 0
> VmFlags: rd wr mr mw me nr mg anon
>
> This information also helps with the following workflow:
> - First enable KSM for all the VMA's of a process with prctl.
> - Then analyze with the above smaps report which VMA's benefit the most
> - Change the application (if possible) to add the corresponding madvise
> calls for the VMA's that benefit the most
>
> Signed-off-by: Stefan Roesch <shr@...kernel.io>
> ---
> Documentation/filesystems/proc.rst | 3 +++
> fs/proc/task_mmu.c | 5 +++++
> 2 files changed, 8 insertions(+)
>
> diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst
> index 7897a7dafcbc..4ef3c0bbf16a 100644
> --- a/Documentation/filesystems/proc.rst
> +++ b/Documentation/filesystems/proc.rst
> @@ -461,6 +461,7 @@ Memory Area, or VMA) there is a series of lines such as the following::
> Private_Dirty: 0 kB
> Referenced: 892 kB
> Anonymous: 0 kB
> + KSM: 0 kB
> LazyFree: 0 kB
> AnonHugePages: 0 kB
> ShmemPmdMapped: 0 kB
> @@ -501,6 +502,8 @@ accessed.
> a mapping associated with a file may contain anonymous pages: when MAP_PRIVATE
> and a page is modified, the file page is replaced by a private anonymous copy.
>
> +"KSM" shows the amount of anonymous memory that has been de-duplicated.
How do we want to treat memory that has been deduplicated into the
shared zeropage?
It would also match this description.
See in mm-stable:
commit 30ff6ed9a65c7e73545319fc15f7bcf9c52457eb
Author: xu xin <xu.xin16@....com.cn>
Date: Tue Jun 13 11:09:28 2023 +0800
ksm: support unsharing KSM-placed zero pages
Patch series "ksm: support tracking KSM-placed zero-pages", v10.
--
Cheers,
David / dhildenb
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