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From: Tejun Heo <tj@kernel.org>
To: Yafang Shao <laoar.shao@gmail.com>
Cc: ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com,
	andrii@kernel.org, martin.lau@linux.dev, song@kernel.org,
	yonghong.song@linux.dev, kpsingh@kernel.org, sdf@google.com,
	haoluo@google.com, jolsa@kernel.org, lizefan.x@bytedance.com,
	hannes@cmpxchg.org, bpf@vger.kernel.org, cgroups@vger.kernel.org
Subject: Re: [PATCH bpf-next 1/4] cgroup, psi: Init PSI of root cgroup to psi_system
Date: Sat, 23 Dec 2023 02:47:55 +0900	[thread overview]
Message-ID: <ZYXLy0AofQyasLkC@mac.lan> (raw)
In-Reply-To: <20231222113102.4148-2-laoar.shao@gmail.com>

Hello,

On Fri, Dec 22, 2023 at 11:30:59AM +0000, Yafang Shao wrote:
> By initializing the root cgroup's psi field to psi_system, we can
> consistently obtain the psi information for all cgroups from the struct
> cgroup.
> 
> Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
> ---
>  include/linux/psi.h    | 2 +-
>  kernel/cgroup/cgroup.c | 5 ++++-
>  2 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/psi.h b/include/linux/psi.h
> index e074587..8f2db51 100644
> --- a/include/linux/psi.h
> +++ b/include/linux/psi.h
> @@ -34,7 +34,7 @@ __poll_t psi_trigger_poll(void **trigger_ptr, struct file *file,
>  #ifdef CONFIG_CGROUPS
>  static inline struct psi_group *cgroup_psi(struct cgroup *cgrp)
>  {
> -	return cgroup_ino(cgrp) == 1 ? &psi_system : cgrp->psi;
> +	return cgrp->psi;
>  }

How have you tested this change? Looking at the code there are other
references to psi_system, e.g. to show it under /proc/pressure/* and to
exempt it from CPU FULL accounting. I don't see how the above change would
be sufficient.

Thanks.

-- 
tejun

  reply	other threads:[~2023-12-22 17:47 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-12-22 11:30 [PATCH bpf-next 0/4] bpf: Add bpf_iter_cpumask Yafang Shao
2023-12-22 11:30 ` [PATCH bpf-next 1/4] cgroup, psi: Init PSI of root cgroup to psi_system Yafang Shao
2023-12-22 17:47   ` Tejun Heo [this message]
2023-12-24  3:14     ` Yafang Shao
2023-12-22 23:49   ` kernel test robot
2023-12-23  7:26   ` kernel test robot
2023-12-22 11:31 ` [PATCH bpf-next 2/4] bpf: Add bpf_iter_cpumask kfuncs Yafang Shao
2024-01-02 22:13   ` Andrii Nakryiko
2024-01-04  2:30     ` Yafang Shao
2023-12-22 11:31 ` [PATCH bpf-next 3/4] bpf: Add new kfunc bpf_cpumask_set_from_pid Yafang Shao
2023-12-22 17:51   ` Tejun Heo
2023-12-24  3:05     ` Yafang Shao
2023-12-22 11:31 ` [PATCH bpf-next 4/4] selftests/bpf: Add selftests for cpumask iter Yafang Shao

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