Re: [patch 7/9] mm: thrash detection-based file cache sizing

[Rik van Riel]

On 01/10/2014 01:10 PM, Johannes Weiner wrote:

> This patch solves one half of the problem by decoupling the ability to
> detect working set changes from the inactive list size.  By
> maintaining a history of recently evicted file pages it can detect
> frequently used pages with an arbitrarily small inactive list size,
> and subsequently apply pressure on the active list based on actual
> demand for cache, not just overall eviction speed.
> 
> Every zone maintains a counter that tracks inactive list aging speed.
> When a page is evicted, a snapshot of this counter is stored in the
> now-empty page cache radix tree slot.  On refault, the minimum access
> distance of the page can be assessed, to evaluate whether the page
> should be part of the active list or not.
> 
> This fixes the VM's blindness towards working set changes in excess of
> the inactive list.  And it's the foundation to further improve the
> protection ability and reduce the minimum inactive list size of 50%.
> 
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>

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

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