linux-kernel - Re: [PATCH v1 3/4] mm/ksm: document smart scan mode

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Message-ID: <aee51f0c-8cf1-d893-c111-e3aa93de2af9@redhat.com>
Date:   Mon, 18 Sep 2023 13:28:38 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Stefan Roesch <shr@...kernel.io>, kernel-team@...com
Cc:     akpm@...ux-foundation.org, hannes@...xchg.org, riel@...riel.com,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v1 3/4] mm/ksm: document smart scan mode

On 12.09.23 19:52, Stefan Roesch wrote:
> This adds documentation for the smart scan mode of KSM.
> 
> Signed-off-by: Stefan Roesch <shr@...kernel.io>
> ---
>   Documentation/admin-guide/mm/ksm.rst | 9 +++++++++
>   1 file changed, 9 insertions(+)
> 
> diff --git a/Documentation/admin-guide/mm/ksm.rst b/Documentation/admin-guide/mm/ksm.rst
> index 776f244bdae4..1762219baf51 100644
> --- a/Documentation/admin-guide/mm/ksm.rst
> +++ b/Documentation/admin-guide/mm/ksm.rst
> @@ -155,6 +155,15 @@ stable_node_chains_prune_millisecs
>           scan. It's a noop if not a single KSM page hit the
>           ``max_page_sharing`` yet.
>   
> +smart_scan
> +        By default KSM checks every candidate page for each scan. It does
> +        not take into account historic information. When smart scan is
> +        enabled, pages that have previously not been de-duplicated get
> +        skipped. How often these pages are skipped depends on how often
> +        de-duplication has already been tried and failed. By default this
> +        optimization is disabled. The ``pages_skipped`` metric shows how
> +        effetive the setting is.
> +
>   The effectiveness of KSM and MADV_MERGEABLE is shown in ``/sys/kernel/mm/ksm/``:
>   
>   general_profit

Reviewed-by: David Hildenbrand <david@...hat.com>

-- 
Cheers,

David / dhildenb