Re: [RFC PATCH] Add Kconfig option for default swappiness

[Jesper Juhl]

On Sun, 31 Oct 2010, Ben Gamari wrote:

> This will allow distributions to tune this important vm parameter in a more
> self-contained manner.
> 
> Signed-off-by: Ben Gamari <bgamari.foss@xxxxxxxxx>
> ---
>  Documentation/sysctl/vm.txt |    2 +-
>  mm/Kconfig                  |   11 +++++++++++
>  mm/vmscan.c                 |    2 +-
>  3 files changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
> index 6c7d18c..792823b 100644
> --- a/Documentation/sysctl/vm.txt
> +++ b/Documentation/sysctl/vm.txt
> @@ -614,7 +614,7 @@ 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.
>  
> -The default value is 60.
> +The default value is 60 (changed with CONFIG_DEFAULT_SWAPINESS).
>  
>  ==============================================================
>  
> diff --git a/mm/Kconfig b/mm/Kconfig
> index 9c61158..729ecec 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -61,6 +61,17 @@ config SPARSEMEM_MANUAL
>  
>  endchoice
>  
> +config DEFAULT_SWAPPINESS
> +	int "Default swappiness"
> +	default "60"
> +	range 0 100
> +	help
> +	  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. Valid values range from 0 to 100.
> +
> +	  If unsure, keep default value of 60.
> +

Perhaps this help text should mention the fact that swapiness setting can 
be changed at runtime (regardless of the set default) by writing to 
/proc/sys/vm/swappiness ???


-- 
Jesper Juhl <jj@xxxxxxxxxxxxx>             http://www.chaosbits.net/
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