On Thu 16-05-13 16:12:38, Tejun Heo wrote:
> On Mon, May 13, 2013 at 09:46:12AM +0200, Michal Hocko wrote:
> > Soft reclaim has been done only for the global reclaim (both background
> > and direct). Since "memcg: integrate soft reclaim tighter with zone
> > shrinking code" there is no reason for this limitation anymore as the
> > soft limit reclaim doesn't use any special code paths and it is a
> > part of the zone shrinking code which is used by both global and
> > targeted reclaims.
> ...
> > Signed-off-by: Michal Hocko <mhocko@xxxxxxx>
>
> Reviewed-by: Tejun Heo <tj@xxxxxxxxxx>
Thanks
>
> Some nitpicks follow.
>
> > /*
> > - * A group is eligible for the soft limit reclaim if it is
> > - * a) is over its soft limit
> > + * A group is eligible for the soft limit reclaim under the given root
> > + * hierarchy if
> > + * a) it is over its soft limit
> > * b) any parent up the hierarchy is over its soft limit
>
> This was added before but in general I think the use of parent for
> ancestor is a bit confusing. Not a big deal but no reason to continue
> it.
$ git grep ancestor mm/memcontrol.c | wc -l
4
$ git grep
parent mm/memcontrol.c | wc -l
80
Yeah, we are used to use parent much more. Maybe it is worth a clean up
on its own but I will stick with the majority in this patch
> > /*
> > - * If any parent up the hierarchy is over its soft limit then we
> > - * have to obey and reclaim from this group as well.
> > + * If any parent up to the root in the hierarchy is over its soft limit
> > + * then we have to obey and reclaim from this group as well.
>
> Prolly using terms ancestors and subtree would make the explanation
> clearer?
As I said earlier we should be explicit about hierarchy as
ancestor/parent (what ever we call it) might or might not be part of the
hierarchy. Yeah, we have that use_hierarchy thingy which we love so
much.
> > static bool mem_cgroup_should_soft_reclaim(struct scan_control *sc)
> > {
> > - return global_reclaim(sc);
> > + return true;
>
> Kinda silly after this change, maybe just modify shrink_zone() like
> the following?
>
> if (IS_ENABLED(CONFIG_MEMCG)) {
> __shrink_zone(zone, sc, true);
> if (sc->nr_scanned == nr_scanned)
> __shrink_zone(zone, sc, false);
> } else {
> __shrink_zone(zone, sc, false);
> }
I plan to build on top of this where mem_cgroup_should_soft_reclaim
would do more than just return true. So I will keep it this way if you
do not mind.
> > @@ -1974,7 +1974,7 @@ __shrink_zone(struct zone *zone, struct scan_control *sc, bool soft_reclaim)
> > struct lruvec *lruvec;
> >
> > if (soft_reclaim &&
> > - !mem_cgroup_soft_reclaim_eligible(memcg)) {
> > + !mem_cgroup_soft_reclaim_eligible(memcg, root)) {
>
> Weird indentation which breaks line and goes over 80 col, why not do
> the following?
>
> if (soft_reclaim &&
> !mem_cgroup_soft_reclaim_eligible(memcg, root)) {
> memcg = mem_cgroup_iter(root, memcg, &reclaim);
> continue;
> }
Hmm, I rely on vim doing the_right_thing usually. I definitely do not
mind to change the formatting. I have fixed this in the first patch
where the code has been introduced and refreshed this patch on top of
that.
I will repost the whole series with reviewed-bys and other acks later
Thanks!
--
Michal Hocko
SUSE Labs
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