Re: [PATCH] vmscan: evict use-once pages first (v2)

[Rik van Riel]

KOSAKI Motohiro wrote:
> Hi
>
> Looks good than previous version. but I have one question.
>
>   
> > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > index eac9577..4471dcb 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -1489,6 +1489,18 @@ static void shrink_zone(int priority, struct zone *zone,
> >                        nr[l] = scan;
> >        }
> >
> > +       /*
> > +        * When the system is doing streaming IO, memory pressure here
> > +        * ensures that active file pages get deactivated, until more
> > +        * than half of the file pages are on the inactive list.
> > +        *
> > +        * Once we get to that situation, protect the system's working
> > +        * set from being evicted by disabling active file page aging.
> > +        * The logic in get_scan_ratio protects anonymous pages.
> > +        */
> > +       if (nr[LRU_INACTIVE_FILE] > nr[LRU_ACTIVE_FILE])
> > +               nr[LRU_ACTIVE_FILE] = 0;
> > +
> >        while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
> >                                        nr[LRU_INACTIVE_FILE]) {
> >                for_each_evictable_lru(l) {
> >     
>
> we handle active_anon vs inactive_anon ratio by shrink_list().
> Why do you insert this logic insert shrink_zone() ?
>   
Good question.  I guess that at lower priority levels, we get to scan
a lot more pages and we could go from having too many inactive
file pages to not having enough in one invocation of shrink_zone().

That makes shrink_list() the better place to implement this, even if
it means doing this comparison more often.

I'll send a new patch this afternoon.
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