Re: [PATCH] mm/compaction: clear total_{migrate,free}_scanned before scanning a new zone

[Yafang Shao <laoar.shao@gmail.com>]

On Tue, Jul 23, 2019 at 1:36 PM Michal Hocko <mhocko@suse.com> wrote:
>
> On Mon 22-07-19 05:54:35, Yafang Shao wrote:
> > total_{migrate,free}_scanned will be added to COMPACTMIGRATE_SCANNED and
> > COMPACTFREE_SCANNED in compact_zone(). We should clear them before scanning
> > a new zone.
> > In the proc triggered compaction, we forgot clearing them.
>
> Wouldn't it be more robust to move zeroying to compact_zone so that none
> of the three current callers has to duplicate (and forget) to do that?
>

Seems that is better.
I will post an update.

Thanks
Yafang

> > Fixes: 7f354a548d1c ("mm, compaction: add vmstats for kcompactd work")
> > Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
> > Cc: David Rientjes <rientjes@google.com>
> > Cc: Vlastimil Babka <vbabka@suse.cz>
> > Cc: Yafang Shao <shaoyafang@didiglobal.com>
> > ---
> >  mm/compaction.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/mm/compaction.c b/mm/compaction.c
> > index 9e1b9ac..a109b45 100644
> > --- a/mm/compaction.c
> > +++ b/mm/compaction.c
> > @@ -2405,8 +2405,6 @@ static void compact_node(int nid)
> >       struct zone *zone;
> >       struct compact_control cc = {
> >               .order = -1,
> > -             .total_migrate_scanned = 0,
> > -             .total_free_scanned = 0,
> >               .mode = MIGRATE_SYNC,
> >               .ignore_skip_hint = true,
> >               .whole_zone = true,
> > @@ -2422,6 +2420,8 @@ static void compact_node(int nid)
> >
> >               cc.nr_freepages = 0;
> >               cc.nr_migratepages = 0;
> > +             cc.total_migrate_scanned = 0;
> > +             cc.total_free_scanned = 0;
> >               cc.zone = zone;
> >               INIT_LIST_HEAD(&cc.freepages);
> >               INIT_LIST_HEAD(&cc.migratepages);
> > --
> > 1.8.3.1
>
> --
> Michal Hocko
> SUSE Labs