Re: [RFC][PATCH] avoid swapping out with swappiness==0

[Rik van Riel]

On 03/02/2012 12:36 PM, Satoru Moriya wrote:
> Sometimes we'd like to avoid swapping out anonymous memory
> in particular, avoid swapping out pages of important process or
> process groups while there is a reasonable amount of pagecache
> on RAM so that we can satisfy our customers' requirements.
>
> OTOH, we can control how aggressive the kernel will swap memory pages
> with /proc/sys/vm/swappiness for global and
> /sys/fs/cgroup/memory/memory.swappiness for each memcg.
>
> But with current reclaim implementation, the kernel may swap out
> even if we set swappiness==0 and there is pagecache on RAM.
>
> This patch changes the behavior with swappiness==0. If we set
> swappiness==0, the kernel does not swap out completely
> (for global reclaim until the amount of free pages and filebacked
> pages in a zone has been reduced to something very very small
> (nr_free + nr_filebacked<  high watermark)).

> Signed-off-by: Satoru Moriya<satoru.moriya@xxxxxxx>

Acked-by: Rik van Riel <riel@xxxxxxxxxx>

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