Re: [PATCH V4 3/6] mm: move MADV_FREE pages into LRU_INACTIVE_FILE list

[Shaohua Li]

On Fri, Feb 24, 2017 at 10:49:39AM +0900, Minchan Kim wrote:
> On Wed, Feb 22, 2017 at 10:50:41AM -0800, 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>
> 
> Other than that Johannes pointed out, code itself looks good to me.
> However, I hope to merge this patch with next one.
> It's enough simple to merge, change behavior(about deactivation),
> mark_page_lazyfree is introduced but there is no callsite to use it
> in this patch.
> 
> I don't think it's worth to separate.

I think it's more clear in this way, doing one thing in one patch.

Thanks,
Shaohua