Re: [PATCH] documentation: clarify dirty_ratio and dirty_background_ratio description

[KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>]

> The current documentation of dirty_ratio and dirty_background_ratio is a
> bit misleading.
> 
> In the documentation we say that they are "a percentage of total system
> memory", but the current page writeback policy, intead, is to apply the
> percentages to the dirtyable memory, that means free pages + reclaimable
> pages.
> 
> Better to be more explicit to clarify this concept.
> 
> Signed-off-by: Andrea Righi <righi.andrea@gmail.com>

looks good to me.



> ---
>  Documentation/filesystems/proc.txt |   11 ++++++-----
>  1 files changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
> index f566ad9..be69c8b 100644
> --- a/Documentation/filesystems/proc.txt
> +++ b/Documentation/filesystems/proc.txt
> @@ -1380,15 +1380,16 @@ causes the kernel to prefer to reclaim dentries and inodes.
>  dirty_background_ratio
>  ----------------------
>  
> -Contains, as a percentage of total system memory, the number of pages at which
> -the pdflush background writeback daemon will start writing out dirty data.
> +Contains, as a percentage of the dirtyable system memory (free pages +
> +reclaimable pages), the number of pages at which the pdflush background
> +writeback daemon will start writing out dirty data.
>  
>  dirty_ratio
>  -----------------
>  
> -Contains, as a percentage of total system memory, the number of pages at which
> -a process which is generating disk writes will itself start writing out dirty
> -data.
> +Contains, as a percentage of the dirtyable system memory (free pages +
> +reclaimable pages), the number of pages at which a process which is generating
> +disk writes will itself start writing out dirty data.
>  
>  dirty_writeback_centisecs
>  -------------------------





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