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From: "Michal Koutný" <mkoutny@suse.com>
To: Hao Xu <haoxu@linux.alibaba.com>
Cc: Jens Axboe <axboe@kernel.dk>, Zefan Li <lizefan.x@bytedance.com>,
	Tejun Heo <tj@kernel.org>, Johannes Weiner <hannes@cmpxchg.org>,
	Pavel Begunkov <asml.silence@gmail.com>,
	io-uring@vger.kernel.org, cgroups@vger.kernel.org,
	Joseph Qi <joseph.qi@linux.alibaba.com>
Subject: Re: [PATCH v4 0/2] refactor sqthread cpu binding logic
Date: Thu, 2 Sep 2021 18:48:08 +0200	[thread overview]
Message-ID: <20210902164808.GA10014@blackbody.suse.cz> (raw)
In-Reply-To: <20210901124322.164238-1-haoxu@linux.alibaba.com>

Hello Hao.

On Wed, Sep 01, 2021 at 08:43:20PM +0800, Hao Xu <haoxu@linux.alibaba.com> wrote:
> This patchset is to enhance sqthread cpu binding logic, we didn't
> consider cgroup setting before. In container environment, theoretically
> sqthread is in its container's task group, it shouldn't occupy cpu out
> of its container.

I see in the discussions that there's struggle to make
set_cpus_allowed_ptr() do what's intended under the given constraints.

IIUC, set_cpus_allowed_ptr() is conventionally used for kernel threads
[1]. But does the sqthread fall into this category? You want to have it
_directly_ associated with a container and its cgroups. It looks to me
more like a userspace thread (from this perspective, not literally). Or
is there a different intention?

It seems to me that reusing the sched_setaffinity() (with all its
checks and race pains/solutions) would be a more universal approach.
(I don't mean calling sched_setaffinity() directly, some parts would
need to be factored separately to this end.) WDYT?


Regards,
Michal

[1] Not only spending their life in kernel but providing some
delocalized kernel service.

  parent reply	other threads:[~2021-09-02 16:48 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-01 12:43 Hao Xu
2021-09-01 12:43 ` [PATCH 1/2] cpuset: add a helper to check if cpu in cpuset of current task Hao Xu
2021-09-01 12:43 ` [PATCH 2/2] io_uring: consider cgroup setting when binding sqpoll cpu Hao Xu
2021-09-01 16:41   ` Tejun Heo
2021-09-01 16:42     ` Tejun Heo
2021-09-03 15:04     ` Hao Xu
2021-09-07 16:54       ` Tejun Heo
2021-09-07 19:28         ` Hao Xu
2021-09-02 16:48 ` Michal Koutný [this message]
2021-09-02 18:00   ` [PATCH v4 0/2] refactor sqthread cpu binding logic Jens Axboe
2021-09-09 12:34     ` Michal Koutný
2021-09-03 14:43   ` Hao Xu

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