Re: [RFC 4/8] Make clear description of putback_lru_page

[Johannes Weiner <hannes@cmpxchg.org>]

On Thu, Apr 28, 2011 at 08:20:32AM +0900, Minchan Kim wrote:
> On Wed, Apr 27, 2011 at 5:11 PM, KAMEZAWA Hiroyuki
> <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> > On Wed, 27 Apr 2011 01:25:21 +0900
> > Minchan Kim <minchan.kim@gmail.com> wrote:
> >
> >> Commonly, putback_lru_page is used with isolated_lru_page.
> >> The isolated_lru_page picks the page in middle of LRU and
> >> putback_lru_page insert the lru in head of LRU.
> >> It means it could make LRU churning so we have to be very careful.
> >> Let's clear description of putback_lru_page.
> >>
> >> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> >> Cc: Mel Gorman <mgorman@suse.de>
> >> Cc: Rik van Riel <riel@redhat.com>
> >> Cc: Andrea Arcangeli <aarcange@redhat.com>
> >> Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
> >
> > seems good...
> > Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> >
> > But is there consensus which side of LRU is tail? head?
> 
> I don't know. I used to think it's head.
> If other guys raise a concern as well, let's talk about it. :)
> Thanks

I suppose we add new pages to the head of the LRU and reclaim old
pages from the tail.

Acked-by: Johannes Weiner <hannes@cmpxchg.org>