Re: [PATCH 06/10] mm: remove unnecessary use-once cache bias from LRU balancing

[Minchan Kim]

On Mon, Jun 06, 2016 at 03:48:32PM -0400, Johannes Weiner wrote:
> When the splitlru patches divided page cache and swap-backed pages
> into separate LRU lists, the pressure balance between the lists was
> biased to account for the fact that streaming IO can cause memory
> pressure with a flood of pages that are used only once. New page cache
> additions would tip the balance toward the file LRU, and repeat access
> would neutralize that bias again. This ensured that page reclaim would
> always go for used-once cache first.
> 
> Since e9868505987a ("mm,vmscan: only evict file pages when we have
> plenty"), page reclaim generally skips over swap-backed memory
> entirely as long as there is used-once cache present, and will apply
> the LRU balancing when only repeatedly accessed cache pages are left -
> at which point the previous use-once bias will have been neutralized.
> 
> This makes the use-once cache balancing bias unnecessary. Remove it.
> 
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: Minchan Kim <minchan@xxxxxxxxxx>