Re: [PATCH V5 3/6] mm: move MADV_FREE pages into LRU_INACTIVE_FILE list

From: Hillf Danton
Date: Mon Feb 27 2017 - 22:22:03 EST


On February 25, 2017 5:32 AM Shaohua Li wrote:
>
> madv MADV_FREE indicate pages are 'lazyfree'. They are still anonymous
> pages, but they can be freed without pageout. To destinguish them
> against normal anonymous pages, we clear their SwapBacked flag.
>
> MADV_FREE pages could be freed without pageout, so they pretty much like
> used once file pages. For such pages, we'd like to reclaim them once
> there is memory pressure. Also it might be unfair reclaiming MADV_FREE
> pages always before used once file pages and we definitively want to
> reclaim the pages before other anonymous and file pages.
>
> To speed up MADV_FREE pages reclaim, we put the pages into
> LRU_INACTIVE_FILE list. The rationale is LRU_INACTIVE_FILE list is tiny
> nowadays and should be full of used once file pages. Reclaiming
> MADV_FREE pages will not have much interfere of anonymous and active
> file pages. And the inactive file pages and MADV_FREE pages will be
> reclaimed according to their age, so we don't reclaim too many MADV_FREE
> pages too. Putting the MADV_FREE pages into LRU_INACTIVE_FILE_LIST also
> means we can reclaim the pages without swap support. This idea is
> suggested by Johannes.
>
> This patch doesn't move MADV_FREE pages to LRU_INACTIVE_FILE list yet to
> avoid bisect failure, next patch will do it.
>
> The patch is based on Minchan's original patch.
>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: Minchan Kim <minchan@xxxxxxxxxx>
> Cc: Hugh Dickins <hughd@xxxxxxxxxx>
> Cc: Rik van Riel <riel@xxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Suggested-by: Johannes Weiner <hannes@xxxxxxxxxxx>
> Signed-off-by: Shaohua Li <shli@xxxxxx>
> ---

Acked-by: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx>