On Thu, Apr 14, 2011 at 5:16 PM, KAMEZAWA Hiroyuki <
kamezawa.hiroyu@jp.fujitsu.com> wrote:

> On Thu, 14 Apr 2011 15:54:21 -0700
> Ying Han <yinghan@google.com> wrote:
>
> > There are two watermarks added per-memcg including "high_wmark" and
> "low_wmark".
> > The per-memcg kswapd is invoked when the memcg's memory
> usage(usage_in_bytes)
> > is higher than the low_wmark. Then the kswapd thread starts to reclaim
> pages
> > until the usage is lower than the high_wmark.
> >
> > Each watermark is calculated based on the hard_limit(limit_in_bytes) for
> each
> > memcg. Each time the hard_limit is changed, the corresponding wmarks are
> > re-calculated. Since memory controller charges only user pages, there is
> > no need for a "min_wmark". The current calculation of wmarks is based on
> > individual tunable low/high_wmark_distance, which are set to 0 by
> default.
> >
> > changelog v4..v3:
> > 1. remove legacy comments
> > 2. rename the res_counter_check_under_high_wmark_limit
> > 3. replace the wmark_ratio per-memcg by individual tunable for both
> wmarks.
> > 4. add comments on low/high_wmark
> > 5. add individual tunables for low/high_wmarks and remove wmark_ratio
> > 6. replace the mem_cgroup_get_limit() call by res_count_read_u64(). The
> first
> > one returns large value w/ swapon.
> >
> > changelog v3..v2:
> > 1. Add VM_BUG_ON() on couple of places.
> > 2. Remove the spinlock on the min_free_kbytes since the consequence of
> reading
> > stale data.
> > 3. Remove the "min_free_kbytes" API and replace it with wmark_ratio based
> on
> > hard_limit.
> >
> > changelog v2..v1:
> > 1. Remove the res_counter_charge on wmark due to performance concern.
> > 2. Move the new APIs min_free_kbytes, reclaim_wmarks into seperate
> commit.
> > 3. Calculate the min_free_kbytes automatically based on the
> limit_in_bytes.
> > 4. make the wmark to be consistant with core VM which checks the free
> pages
> > instead of usage.
> > 5. changed wmark to be boolean
> >
> > Signed-off-by: Ying Han <yinghan@google.com>
>
> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
>
> some nitpick below.
>
>
>
> > ---
> >  include/linux/memcontrol.h  |    1 +
> >  include/linux/res_counter.h |   78
> +++++++++++++++++++++++++++++++++++++++++++
> >  kernel/res_counter.c        |    6 +++
> >  mm/memcontrol.c             |   48 ++++++++++++++++++++++++++
> >  4 files changed, 133 insertions(+), 0 deletions(-)
> >
> > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> > index 5a5ce70..3ece36d 100644
> > --- a/include/linux/memcontrol.h
> > +++ b/include/linux/memcontrol.h
> > @@ -82,6 +82,7 @@ int task_in_mem_cgroup(struct task_struct *task, const
> struct mem_cgroup *mem);
> >
> >  extern struct mem_cgroup *try_get_mem_cgroup_from_page(struct page
> *page);
> >  extern struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);
> > +extern int mem_cgroup_watermark_ok(struct mem_cgroup *mem, int
> charge_flags);
> >
> >  static inline
> >  int mm_match_cgroup(const struct mm_struct *mm, const struct mem_cgroup
> *cgroup)
> > diff --git a/include/linux/res_counter.h b/include/linux/res_counter.h
> > index c9d625c..77eaaa9 100644
> > --- a/include/linux/res_counter.h
> > +++ b/include/linux/res_counter.h
> > @@ -39,6 +39,14 @@ struct res_counter {
> >        */
> >       unsigned long long soft_limit;
> >       /*
> > +      * the limit that reclaim triggers.
> > +      */
> > +     unsigned long long low_wmark_limit;
> > +     /*
> > +      * the limit that reclaim stops.
> > +      */
> > +     unsigned long long high_wmark_limit;
> > +     /*
> >        * the number of unsuccessful attempts to consume the resource
> >        */
> >       unsigned long long failcnt;
> > @@ -55,6 +63,9 @@ struct res_counter {
> >
> >  #define RESOURCE_MAX (unsigned long long)LLONG_MAX
> >
> > +#define CHARGE_WMARK_LOW     0x01
> > +#define CHARGE_WMARK_HIGH    0x02
> > +
> >  /**
> >   * Helpers to interact with userspace
> >   * res_counter_read_u64() - returns the value of the specified member.
> > @@ -92,6 +103,8 @@ enum {
> >       RES_LIMIT,
> >       RES_FAILCNT,
> >       RES_SOFT_LIMIT,
> > +     RES_LOW_WMARK_LIMIT,
> > +     RES_HIGH_WMARK_LIMIT
> >  };
> >
> >  /*
> > @@ -147,6 +160,24 @@ static inline unsigned long long
> res_counter_margin(struct res_counter *cnt)
> >       return margin;
> >  }
> >
> > +static inline bool
> > +res_counter_high_wmark_limit_check_locked(struct res_counter *cnt)
> > +{
> > +     if (cnt->usage < cnt->high_wmark_limit)
> > +             return true;
> > +
> > +     return false;
> > +}
> > +
> > +static inline bool
> > +res_counter_low_wmark_limit_check_locked(struct res_counter *cnt)
> > +{
> > +     if (cnt->usage < cnt->low_wmark_limit)
> > +             return true;
> > +
> > +     return false;
> > +}
>
> I like res_counter_under_low_wmark_limit_locked() rather than this name.
>

Thanks for review. Will change this on the next post.

--Ying

>
> Thanks,
> -Kame
>
>