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From:   Vipin Sharma <vipinsh@google.com>
Date:   Wed, 15 Sep 2021 10:04:18 -0700
Message-ID: <CAHVum0d657HeoSyXS9RGW8YHkwJFmvLQ6ebwYy_wVnR0gM8uPQ@mail.gmail.com>
Subject: Re: [PATCH v3 1/3] misc_cgroup: introduce misc.events to count failures
To:     brookxu <brookxu.cn@gmail.com>
Cc:     tj@kernel.org, lizefan.x@bytedance.com, hannes@cmpxchg.org,
        mkoutny@suse.com, corbet@lwn.net, linux-kernel@vger.kernel.org,
        cgroups@vger.kernel.org, linux-doc@vger.kernel.org
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On Tue, Sep 14, 2021 at 7:18 PM brookxu <brookxu.cn@gmail.com> wrote:
>
> From: Chunguang Xu <brookxu@tencent.com>
>
> Introduce misc.events to make it easier for us to understand
> the pressure of resources. Currently only the 'max' event is
> implemented, which indicates the times the resource is about
> to exceeds the max limit.
>
> Signed-off-by: Chunguang Xu <brookxu@tencent.com>
> ---
>
> v3: remove misc.events.local.
> v2: remove cgroup v1 files.
>
>  include/linux/misc_cgroup.h |  5 +++++
>  kernel/cgroup/misc.c        | 24 ++++++++++++++++++++++++
>  2 files changed, 29 insertions(+)
>
> diff --git a/include/linux/misc_cgroup.h b/include/linux/misc_cgroup.h
> index da2367e..091f2d2 100644
> --- a/include/linux/misc_cgroup.h
> +++ b/include/linux/misc_cgroup.h
> @@ -36,6 +36,7 @@ enum misc_res_type {
>  struct misc_res {
>         unsigned long max;
>         atomic_long_t usage;
> +       atomic_long_t events;
>         bool failed;
>  };
>
> @@ -46,6 +47,10 @@ struct misc_res {
>   */
>  struct misc_cg {
>         struct cgroup_subsys_state css;
> +
> +       /* misc.events */
> +       struct cgroup_file events_file;
> +
>         struct misc_res res[MISC_CG_RES_TYPES];
>  };
>
> diff --git a/kernel/cgroup/misc.c b/kernel/cgroup/misc.c
> index ec02d96..4b2b492 100644
> --- a/kernel/cgroup/misc.c
> +++ b/kernel/cgroup/misc.c
> @@ -171,6 +171,11 @@ int misc_cg_try_charge(enum misc_res_type type, struct misc_cg *cg,
>         return 0;
>
>  err_charge:
> +       for (j = i; j; j = parent_misc(j)) {
> +               atomic_long_inc(&j->res[type].events);
> +               cgroup_file_notify(&j->events_file);
> +       }
> +
>         for (j = cg; j != i; j = parent_misc(j))
>                 misc_cg_cancel_charge(type, j, amount);
>         misc_cg_cancel_charge(type, i, amount);
> @@ -335,6 +340,19 @@ static int misc_cg_capacity_show(struct seq_file *sf, void *v)
>         return 0;
>  }
>
> +static int misc_events_show(struct seq_file *sf, void *v)
> +{
> +       struct misc_cg *cg = css_misc(seq_css(sf));
> +       unsigned long events, i;
> +
> +       for (i = 0; i < MISC_CG_RES_TYPES; i++) {
> +               events = atomic_long_read(&cg->res[i].events);
> +               if (READ_ONCE(misc_res_capacity[i]) || events)
> +                       seq_printf(sf, "%s.max %lu\n", misc_res_name[i], events);
> +       }
> +       return 0;
> +}
> +
>  /* Misc cgroup interface files */
>  static struct cftype misc_cg_files[] = {
>         {
> @@ -353,6 +371,12 @@ static int misc_cg_capacity_show(struct seq_file *sf, void *v)
>                 .seq_show = misc_cg_capacity_show,
>                 .flags = CFTYPE_ONLY_ON_ROOT,
>         },
> +       {
> +               .name = "events",
> +               .flags = CFTYPE_NOT_ON_ROOT,
> +               .file_offset = offsetof(struct misc_cg, events_file),
> +               .seq_show = misc_events_show,
> +       },
>         {}
>  };
>
> --
> 1.8.3.1
>

Reviewed-by: Vipin Sharma <vipinsh@google.com>