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Message-ID: <52E2B6BB.5040806@infradead.org>
Date: Fri, 24 Jan 2014 10:53:47 -0800
From: Randy Dunlap <rdunlap@...radead.org>
To: Aaron Tomlin <atomlin@...hat.com>, mingo@...nel.org
CC: linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
rientjes@...gle.com, mingo@...hat.com, oleg@...hat.com,
riel@...hat.com, bmr@...hat.com, akpm@...ux-foundation.org
Subject: Re: [PATCH] mm: Document improved handling of swappiness==0
On 01/24/2014 07:13 AM, Aaron Tomlin wrote:
> Prior to upstream commit fe35004f ("[mm] avoid swapping out
> with swappiness==0") setting swappiness to 0, reclaim code
> could still evict recently used user anonymous memory to swap
> even though there is a significant amount of RAM used for page
> cache.
>
> The behaviour of setting swappiness to 0 has since changed.
> When set, the reclaim code does not initiate swap until the
> amount of free pages and file-backed pages, is less than the
> high water mark in a zone.
>
> Let's update the documentation to reflect this.
>
> Signed-off-by: Aaron Tomlin <atomlin@...hat.com>
> Acked-by: Rik van Riel <riel@...hat.com>
> Acked-by: Bryn M. Reeves <bmr@...hat.com>
> ---
> Documentation/sysctl/vm.txt | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
> index 9f5481b..38388ee 100644
> --- a/Documentation/sysctl/vm.txt
> +++ b/Documentation/sysctl/vm.txt
> @@ -696,7 +696,9 @@ swappiness
>
> This control is used to define how aggressive the kernel will swap
> memory pages. Higher values will increase agressiveness, lower values
> -decrease the amount of swap.
> +decrease the amount of swap. A value of 0 instructs the kernel not to
> +initiate swap until the amount of free and file-backed pages, is less
drop the comma ^
> +than the high water mark in a zone.
>
> The default value is 60.
>
>
--
~Randy
--
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