linux-kernel - Re: [PATCH] perf/core: Update cgroup time with descendants

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Message-ID: <CALPjY3ko2MUYFBgfT9QqZFqGe+G=jTWhs9zb+KjDS8s32K9pkA@mail.gmail.com>
Date:   Tue, 19 Sep 2017 10:02:50 +0800
From:   Lin Xiulei <linxiulei@...il.com>
To:     yang_oliver@...mail.com, Peter Zijlstra <peterz@...radead.org>,
        mingo@...hat.com, acme@...nel.org,
        alexander.shishkin@...ux.intel.com, linux-kernel@...r.kernel.org,
        tglx@...utronix.de, Stephane Eranian <eranian@...il.com>,
        torvalds@...ux-foundation.org, Jiri Olsa <jolsa@...hat.com>
Cc:     "leilei.lin" <leilei.lin@...baba-inc.com>
Subject: Re: [PATCH] perf/core: Update cgroup time with descendants

Add steps of reproducing

1
```
mkdir /sys/fs/cgroup/perf_event/root1
mkdir /sys/fs/cgroup/perf_event/root1/leaf1
```
2  $pid is any running process
```
echo $pid > /sys/fs/cgroup/perf_event/root1/cgroup.procs
```

3
```
perf stat -e cycles -G root1 -a -I 1000
```

You shall get 0 cycles from it, which should have been cycles of $pid

2017-09-14 15:03 GMT+08:00  <linxiulei@...il.com>:
> From: "leilei.lin" <leilei.lin@...baba-inc.com>
>
> This fix updating cgroup time when event is being scheduled in
> by cgroup descendants
>
> Signed-off-by: leilei.lin <leilei.lin@...baba-inc.com>
> ---
>  kernel/events/core.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index 3e691b7..6f6bd1e 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -662,7 +662,9 @@ static inline void update_cgrp_time_from_event(struct perf_event *event)
>         /*
>          * Do not update time when cgroup is not active
>          */
> -       if (cgrp == event->cgrp)
> +       if (cgrp == event->cgrp ||
> +               cgroup_is_descendant(cgrp->css.cgroup,
> +                       event->cgrp->css.cgroup))
>                 __update_cgrp_time(event->cgrp);
>  }
>
> --
> 2.8.4.31.g9ed660f
>