Re: [PATCH V3 3/7] New APIs to adjust per-memcg wmarks

[Ying Han <yinghan@google.com>]

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On Wed, Apr 13, 2011 at 1:30 AM, KAMEZAWA Hiroyuki <
kamezawa.hiroyu@jp.fujitsu.com> wrote:

> On Wed, 13 Apr 2011 00:03:03 -0700
> Ying Han <yinghan@google.com> wrote:
>
> > Add wmark_ratio and reclaim_wmarks APIs per-memcg. The wmark_ratio
> > adjusts the internal low/high wmark calculation and the reclaim_wmarks
> > exports the current value of watermarks. By default, the wmark_ratio is
> > set to 0 and the watermarks are equal to the hard_limit(limit_in_bytes).
> >
> > $ cat /dev/cgroup/A/memory.wmark_ratio
> > 0
> >
> > $ cat /dev/cgroup/A/memory.limit_in_bytes
> > 524288000
> >
> > $ echo 80 >/dev/cgroup/A/memory.wmark_ratio
> >
> > $ cat /dev/cgroup/A/memory.reclaim_wmarks
> > low_wmark 393216000
> > high_wmark 419430400
> >
>
> I think havig _ratio_ will finally leads us to a tragedy as dirty_ratio,
> a complicated interface.
>
> For memcg, I'd like to have only _bytes.
>
> And, as I wrote in previous mail, how about setting _distance_ ?
>
>   memory.low_wmark_distance_in_bytes .... # hard_limit - low_wmark.
>   memory.high_wmark_distance_in_bytes ... # hard_limit - high_wmark.
>
> Anwyay, percent is too big unit.
>

Replied to your comment on "Add per memcg reclaim watermarks". I have no
problem to make the
wmark individual tunable. One thing to confirm before making the change is
to have:


memory.low_wmark_distance_in_bytes .... # min(hard_limit, soft_limit) -
> low_wmark
> memory.high_wmark_distance_in_bytes ... # min(hard_limit, soft_limit) -
> high_wmark.
>

And also, some checks on soft_limit are needed. If "soft_limit" == 0, use
hard_limit

--Ying


> Thanks,
> -Kame
>
>
> > changelog v3..v2:
> > 1. replace the "min_free_kbytes" api with "wmark_ratio". This is part of
> > feedbacks
> >
> > Signed-off-by: Ying Han <yinghan@google.com>
> > ---
> >  mm/memcontrol.c |   49 +++++++++++++++++++++++++++++++++++++++++++++++++
> >  1 files changed, 49 insertions(+), 0 deletions(-)
> >
> > diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> > index 664cdc5..36ae377 100644
> > --- a/mm/memcontrol.c
> > +++ b/mm/memcontrol.c
> > @@ -3983,6 +3983,31 @@ static int mem_cgroup_swappiness_write(struct
> cgroup *cgrp, struct cftype *cft,
> >       return 0;
> >  }
> >
> > +static u64 mem_cgroup_wmark_ratio_read(struct cgroup *cgrp, struct
> cftype *cft)
> > +{
> > +     struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
> > +
> > +     return get_wmark_ratio(memcg);
> > +}
> > +
> > +static int mem_cgroup_wmark_ratio_write(struct cgroup *cgrp, struct
> cftype *cfg,
> > +                                  u64 val)
> > +{
> > +     struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
> > +     struct mem_cgroup *parent;
> > +
> > +     if (cgrp->parent == NULL)
> > +             return -EINVAL;
> > +
> > +     parent = mem_cgroup_from_cont(cgrp->parent);
> > +
> > +     memcg->wmark_ratio = val;
> > +
> > +     setup_per_memcg_wmarks(memcg);
> > +     return 0;
> > +
> > +}
> > +
> >  static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
> >  {
> >       struct mem_cgroup_threshold_ary *t;
> > @@ -4274,6 +4299,21 @@ static void mem_cgroup_oom_unregister_event(struct
> cgroup *cgrp,
> >       mutex_unlock(&memcg_oom_mutex);
> >  }
> >
> > +static int mem_cgroup_wmark_read(struct cgroup *cgrp,
> > +     struct cftype *cft,  struct cgroup_map_cb *cb)
> > +{
> > +     struct mem_cgroup *mem = mem_cgroup_from_cont(cgrp);
> > +     u64 low_wmark, high_wmark;
> > +
> > +     low_wmark = res_counter_read_u64(&mem->res, RES_LOW_WMARK_LIMIT);
> > +     high_wmark = res_counter_read_u64(&mem->res, RES_HIGH_WMARK_LIMIT);
> > +
> > +     cb->fill(cb, "low_wmark", low_wmark);
> > +     cb->fill(cb, "high_wmark", high_wmark);
> > +
> > +     return 0;
> > +}
> > +
> >  static int mem_cgroup_oom_control_read(struct cgroup *cgrp,
> >       struct cftype *cft,  struct cgroup_map_cb *cb)
> >  {
> > @@ -4377,6 +4417,15 @@ static struct cftype mem_cgroup_files[] = {
> >               .unregister_event = mem_cgroup_oom_unregister_event,
> >               .private = MEMFILE_PRIVATE(_OOM_TYPE, OOM_CONTROL),
> >       },
> > +     {
> > +             .name = "wmark_ratio",
> > +             .write_u64 = mem_cgroup_wmark_ratio_write,
> > +             .read_u64 = mem_cgroup_wmark_ratio_read,
> > +     },
> > +     {
> > +             .name = "reclaim_wmarks",
> > +             .read_map = mem_cgroup_wmark_read,
> > +     },
> >  };
> >
> >  #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
> > --
> > 1.7.3.1
> >
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>

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