Re: [PATCH 4/7] memcg fix scan ratio with small memcg.

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Mon, 25 Apr 2011 10:35:39 -0700
Ying Han <yinghan@google.com> wrote:

> On Mon, Apr 25, 2011 at 2:34 AM, KAMEZAWA Hiroyuki <
> kamezawa.hiroyu@jp.fujitsu.com> wrote:
> 
> >
> > At memcg memory reclaim, get_scan_count() may returns [0, 0, 0, 0]
> > and no scan was not issued at the reclaim priority.
> >
> > The reason is because memory cgroup may not be enough big to have
> > the number of pages, which is greater than 1 << priority.
> >
> > Because priority affects many routines in vmscan.c, it's better
> > to scan memory even if usage >> priority < 0.
> > From another point of view, if memcg's zone doesn't have enough memory
> > which
> > meets priority, it should be skipped. So, this patch creates a temporal
> > priority
> > in get_scan_count() and scan some amount of pages even when
> > usage is small. By this, memcg's reclaim goes smoother without
> > having too high priority, which will cause unnecessary congestion_wait(),
> > etc.
> >
> > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> > ---
> >  include/linux/memcontrol.h |    6 ++++++
> >  mm/memcontrol.c            |    5 +++++
> >  mm/vmscan.c                |   11 +++++++++++
> >  3 files changed, 22 insertions(+)
> >
> > Index: memcg/include/linux/memcontrol.h
> > ===================================================================
> > --- memcg.orig/include/linux/memcontrol.h
> > +++ memcg/include/linux/memcontrol.h
> > @@ -152,6 +152,7 @@ unsigned long mem_cgroup_soft_limit_recl
> >                                                gfp_t gfp_mask,
> >                                                unsigned long
> > *total_scanned);
> >  u64 mem_cgroup_get_limit(struct mem_cgroup *mem);
> > +u64 mem_cgroup_get_usage(struct mem_cgroup *mem);
> >
> >  void mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item
> > idx);
> >  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> > @@ -357,6 +358,11 @@ u64 mem_cgroup_get_limit(struct mem_cgro
> >        return 0;
> >  }
> >
> > +static inline u64 mem_cgroup_get_limit(struct mem_cgroup *mem)
> > +{
> > +       return 0;
> > +}
> > +
> >
> 
> should be  mem_cgroup_get_usage()
> 

Ah, yes. thanks.

-Kame

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