Re: [PATCH] mm/vmscan.c: avoid recording the original scan targets in shrink_lruvec()

Minchan Kim
2014-06-10T00:24:13Z

On Tue, Jun 10, 2014 at 08:10:51AM +0800, Chen Yucong wrote:
> On Tue, 2014-06-10 at 08:24 +0900, Minchan Kim wrote:
> > Hello,
> >
> > On Mon, Jun 09, 2014 at 09:27:16PM +0800, Chen Yucong wrote:
> > > Via https://lkml.org/lkml/2013/4/10/334 , we can find that recording the
> > > original scan targets introduces extra 40 bytes on the stack. This patch
> > > is able to avoid this situation and the call to memcpy(). At the same time,
> > > it does not change the relative design idea.
> > >
> > > ratio = original_nr_file / original_nr_anon;
> > >
> > > If (nr_file > nr_anon), then ratio = (nr_file - x) / nr_anon.
> > > x = nr_file - ratio * nr_anon;
> > >
> > > if (nr_file <= nr_anon), then ratio = nr_file / (nr_anon - x).
> > > x = nr_anon - nr_file / ratio;
> >
> > Nice cleanup!
> >
> > Below one nitpick.
> >
>
> >
> > If both nr_file and nr_anon are zero, then the nr_anon could be zero
> > if HugePage are reclaimed so that it could pass the below check
> >
> > if (nr_reclaimed < nr_to_reclaim || scan_adjusted)
> >
> >
> The Mel Gorman's patch has already handled this situation you're
> describing. It's called:
>
> mm: vmscan: use proportional scanning during direct reclaim and full
> scan at DEF_PRIORITY

It seems I was far away from vmscan.c for a while.
Thanks for the pointing out. So,

Acked-by: Minchan Kim <minchan@kernel.org>

--
Kind regards,
Minchan Kim